migrate hints system to a localized markdown-based architecture and refactor related UI components

app/src/main/assets/hints/api_key_hint.md

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+# How to Connect to an AI Model
+
+This guide explains how to connect your app to an AI model using an API key.
+
+## Getting Started
+
+To use AI models in your app, you need to provide a valid API key. This key authenticates your requests and tracks your usage.
+
+> **Note:** Keep your API key secure and never share it publicly.
+
+## Key Status Indicators
+
+Your API key can be in one of two states:
+
+| Status | Icon | Meaning |
+|--------|------|---------|
+| Active | ✅ | Key is valid and working |
+| Missing | ⚠️ | Key is not set or was cleared |
+
+### Active Key
+
+When your API key is active, you can use all available AI models. The system will display a checkmark indicator next to the key status.
+
+### Missing Key
+
+If the key is missing or cleared, you won't be able to make API requests. You'll see a warning indicator, and any attempt to use AI features will prompt you to add a valid key.
+
+## Connecting Your AI Model
+
+1. **Navigate to Settings** → API Key section
+2. **Enter your API key** in the provided field
+3. **Save** the configuration
+4. **Verify** the connection is successful
+
+## Troubleshooting
+
+If you're having issues with your API key:
+
+1. **Verify the key is correct** - Check for typos or extra spaces
+2. **Ensure the key has proper permissions** - Some models require additional access
+3. **Check your quota** - You may have exceeded your usage limits
+4. **Try regenerating the key** - If all else fails, generate a new key from your provider
+
+```json
+// Example API key format
+{
+  "api_key": "sk-xxxxxxxxxxxxxxxxxxxx"
+}
+```
+
+---
+
+**Need more help?** Check our documentation or contact support.

app/src/main/assets/hints/category_hint.md

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+# Understanding Categories
+
+Learn how to use categories to organize and filter your vocabulary effectively.
+
+## What Are Categories?
+
+Categories help you organize your vocabulary into meaningful groups. You can use them to track words by topic, difficulty, or any custom system that works for you.
+
+## Two Types of Categories
+
+### List Categories
+
+List categories are simple groupings of vocabulary items. Words in a list category stay together regardless of their learning stage.
+
+**Use cases:**
+- Group words by topic (e.g., "Food", "Travel", "Business")
+- Create custom decks for specific purposes
+- Organize words by source (e.g., "Book: Harry Potter")
+
+### Filter Categories
+
+Filter categories automatically include all vocabulary items that match certain criteria. Words are dynamically added based on the filter rules.
+
+**Use cases:**
+- Filter by learning stage (e.g., "Words I'm learning")
+- Filter by mastery level (e.g., "Words I need to review")
+- Combine multiple criteria for complex filtering
+
+## Creating Categories
+
+1. **Tap the + button** to create a new category
+2. **Choose the type** - List or Filter
+3. **Add a name** and optional description
+4. **Set the rules** (for filter categories)
+5. **Save** your category
+
+## Managing Categories
+
+- **Edit** - Tap a category to modify its settings
+- **Delete** - Swipe left and tap delete (words are not deleted)
+- **Reorder** - Drag to change display order
+
+## Tips
+
+> **Pro Tip:** Use filter categories for learning stages to automatically track progress across all words at a certain level.
+
+---
+
+*Need more help? Check our documentation.*

app/src/main/assets/hints/dictionary_hint.md

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+# Dictionary Options
+
+Learn how to configure and use the dictionary options for better translations.
+
+## What Are Dictionary Options?
+
+Dictionary options allow you to customize how translations appear and how the dictionary feature works.
+
+## Key Features
+
+### Synonyms
+
+Enable synonyms to see alternative translations:
+- Toggle the **Synonyms** switch
+- View multiple translation options
+- Choose the most appropriate meaning
+
+### Part of Speech
+
+Display grammatical information:
+- See if a word is noun, verb, adjective
+- Helps understand context
+- Available for supported languages
+
+### Example Sentences
+
+View usage examples:
+- See words in context
+- Learn proper usage patterns
+- Understand nuances
+
+## Configuration
+
+### Enable/Disable Features
+
+1. Go to Settings → Dictionary
+2. Toggle desired options on/off
+3. Changes apply immediately
+
+### Custom Dictionary
+
+Add custom entries:
+- Tap the **+** button
+- Enter word and translation
+- Save to your personal dictionary
+
+---
+
+*Tip: Enable all options for the richest translation experience!*

app/src/main/assets/hints/import_hint.md

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+# Import Vocabulary with AI
+
+Generate vocabulary lists automatically using AI assistance.
+
+## Getting Started
+
+Use AI to quickly create vocabulary lists from your learning goals.
+
+## Step-by-Step Guide
+
+### Step 1: Enter Search Term
+
+Type a topic, theme, or concept for your vocabulary list:
+- Be specific for better results
+- Example: "German food and restaurant phrases"
+- Example: "Business vocabulary for meetings"
+
+### Step 2: Select Languages
+
+Choose source and target languages:
+- **Source language** - The language you're learning from
+- **Target language** - Your native language
+
+### Step 3: Set Amount
+
+Choose how many words to generate:
+- Slide to select 1-25 words
+- More words = longer processing time
+- Start small for your first import
+
+### Step 4: Generate
+
+Tap the generate button:
+- AI creates the vocabulary list
+- Review each entry before saving
+- Edit any translations if needed
+
+## After Generation
+
+Once generated, you can:
+
+- **Review** - Check each word-translation pair
+- **Edit** - Correct any mistakes
+- **Delete** - Remove unwanted entries
+- **Import All** - Add all to your vocabulary
+
+## Tips
+
+> **Pro Tip:** Start with 10 words per import to get familiar with the feature.
+
+---
+
+*Need help? Check our vocabulary management guide.*

app/src/main/assets/hints/learning_stages_hint.md

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+# Learning Stages
+
+Understand how vocabulary progresses through different learning stages to optimize your study sessions.
+
+## The Learning Stages
+
+Your vocabulary items move through these stages as you learn:
+
+| Stage | Name | Interval | Description |
+|-------|------|----------|-------------|
+| 🌟 | New | - | Just added vocabulary |
+| 📅 | Stage 1 | 1 day | Recently learned |
+| 📅 | Stage 2 | 3 days | Reinforcement |
+| 📅 | Stage 3 | 1 week | Consolidation |
+| 📅 | Stage 4 | 2 weeks | Deep learning |
+| 📅 | Stage 5 | 1 month | Mastery |
+| ✅ | Learned | ∞ | Fully learned |
+
+## How It Works
+
+### Answer Correctly ✅
+
+When you correctly identify a word during review:
+- The word **moves forward** to the next stage
+- The interval until next review **increases**
+- This helps you focus on words that need more practice
+
+### Answer Incorrectly ❌
+
+When you make a mistake:
+- The word **moves back** one or more stages
+- The review interval **decreases**
+- This ensures you practice challenging words more often
+
+## Customization
+
+All intervals and rules can be customized in Settings:
+
+- **Adjust intervals** for each stage
+- **Change how many stages** to regress on errors
+- **Skip stages** for certain word types
+- **Enable/disable** specific stages
+
+## Visual Progress
+
+The app displays your progress visually:
+- Stage indicators show current status
+- Progress bars track advancement
+- Statistics display overall mastery
+
+---
+
+*Tip: Consistent daily practice is key to moving words through all stages!*

app/src/main/assets/hints/review_hint.md

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+# Review Vocabulary
+
+Master your vocabulary through systematic review sessions.
+
+## The Review Screen
+
+When you start a review session, you'll see:
+
+- The **source word** to translate
+- Options to reveal the **translation**
+- Buttons to indicate your **knowledge level**
+
+## How to Review
+
+### 1. View the Word
+
+Read the source word carefully:
+- Pay attention to the spelling
+- Think of the meaning
+- Recall the translation
+
+### 2. Reveal Translation
+
+Tap to show the translation:
+- Compare with your recall
+- Note any differences
+- Learn from mistakes
+
+### 3. Rate Your Knowledge
+
+Rate how well you knew the answer:
+
+| Button | Meaning | Action |
+|--------|---------|--------|
+| 😓 | Hard | Moves back stages |
+| 🤔 | Okay | Stays current |
+| ✅ | Easy | Advances stage |
+
+## Review Statistics
+
+Track your progress:
+- **Cards reviewed** - Total in session
+- **Accuracy** - Percentage correct
+- **Time spent** - Learning duration
+
+## Best Practices
+
+### Daily Reviews
+
+- Review **every day** for best results
+- Complete **all due** cards before adding new
+- Focus on **problem areas**
+
+### Spaced Repetition
+
+The system uses spaced repetition:
+- **Hard cards** - Review sooner (1-2 days)
+- **Okay cards** - Review normally (as scheduled)
+- **Easy cards** - Review later (weeks)
+
+---
+
+*Consistent daily review is the key to long-term retention!*

app/src/main/assets/hints/sorting_hint.md

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+# Sorting Vocabulary
+
+Learn how to efficiently sort and organize new vocabulary as you add them.
+
+## The Sorting Screen
+
+When you import vocabulary, you'll see the sorting screen where you can:
+
+- Review each word-translation pair
+- Decide the next action for each item
+- Handle duplicates and conflicts
+
+## Actions
+
+### ✅ Mark as Learned
+
+Move the word directly to Stage 1:
+- The word enters your learning queue
+- You'll review it according to the learning schedule
+
+### 🗑️ Delete
+
+Remove the word entirely:
+- Use for duplicates or unwanted entries
+- This action is permanent
+
+### 📝 Edit
+
+Tap on any word or translation to edit:
+- Correct typos
+- Improve translations
+- Add additional context
+
+## Duplicate Handling
+
+When duplicates are detected:
+
+| Icon | Meaning |
+|------|---------|
+| ⚠️ | Duplicate detected |
+| ✅ | Original entry |
+| ❌ | Duplicate entry |
+
+**Options for duplicates:**
+- Keep only the original
+- Keep the newer entry
+- Keep both (merge)
+- Delete the duplicate
+
+## Helper Features
+
+### Remove Articles
+
+Toggle to automatically strip articles from words:
+- "der Hund" → "Hund"
+- "the dog" → "dog"
+- Useful for cleaner vocabulary lists
+
+### Quick Actions
+
+Use quick action buttons for bulk operations:
+- **Skip All** - Review later
+- **Learn All** - Add all to Stage 1
+- **Delete Duplicates** - Auto-remove duplicates
+
+## Tips
+
+> **Pro Tip:** Review carefully before sorting. Once sorted, you can still edit words in the vocabulary list.
+
+---
+
+*For more tips, check our vocabulary management guide.*

app/src/main/assets/hints/translation_hint.md

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+# Translation Features
+
+Discover the powerful translation capabilities of this app.
+
+## Alternative Translations
+
+Sometimes a word has multiple meanings:
+- Tap the **Show alternatives** option
+- See all possible translations
+- Choose the most appropriate context
+
+## Custom Prompts
+
+Customize how translations are generated:
+
+### Create Custom Prompt
+
+1. Go to Settings → Translation
+2. Tap **Add Custom Prompt**
+3. Write your prompt template
+4. Save and use in translations
+
+### Example Prompts
+
+```
+Translate {word} as used in {context}
+
+Provide formal translation of: {word}
+
+Casual translation for: {word}
+```
+
+## Multiple Translation Services
+
+Use different translation backends:
+
+| Service | Best For | Languages |
+|---------|----------|-----------|
+| AI Models | Context-aware | Many |
+| Dictionary | Quick lookup | Limited |
+| Online API | Accuracy | All |
+
+## Translation History
+
+Track all your translations:
+- Automatically saved
+- Search by word or date
+- Export for review
+
+## Text-to-Speech (TTS)
+
+Hear words pronounced:
+- Tap the **speaker icon**
+- Choose voice for each language
+- Adjust speed as needed
+
+## Quick Actions
+
+Fast access to common tasks:
+
+- **Copy** - Copy translation to clipboard
+- **Add** - Add directly to vocabulary
+- **Share** - Send to other apps
+
+---
+
+*Pro Tip: Use custom prompts for domain-specific vocabulary!*

app/src/main/assets/hints/vocabulary_progress_hint.md

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+# Vocabulary Progress Tracking
+
+Monitor your vocabulary learning journey with detailed progress statistics.
+
+## Progress Overview
+
+Track your learning with these key metrics:
+
+### Words Learned
+
+- Total words added to your vocabulary
+- Words currently in each learning stage
+- Words marked as fully learned
+
+### Learning Streak
+
+- Days since you started learning
+- Current streak count
+- Best streak achieved
+
+### Review Statistics
+
+- Words reviewed today
+- Accuracy rate per session
+- Words due for review
+
+## Progress Tracking Features
+
+### 📊 Dashboard
+
+View your overall progress at a glance:
+- Total vocabulary count
+- Mastery percentage
+- Recent activity summary
+
+### 📈 Statistics
+
+Detailed analytics include:
+- Learning rate over time
+- Stage distribution
+- Accuracy trends
+- Time spent studying
+
+### 🎯 Goals
+
+Set and track learning goals:
+- Daily word targets
+- Weekly review quotas
+- Mastery milestones
+
+## Learning Stages Summary
+
+| Stage | Count | Percentage |
+|-------|-------|------------|
+| New | X | X% |
+| Learning | X | X% |
+| Mastered | X | X% |
+
+## Review System
+
+The review system helps you:
+
+1. **Prioritize** - Shows words due for review first
+2. **Space** - Optimizes review timing for retention
+3. **Track** - Records your performance over time
+
+## Customization
+
+Customize your progress tracking:
+
+- **Select metrics** to display on dashboard
+- **Set goals** for personalized targets
+- **Export data** for external analysis
+- **Reset progress** if starting fresh
+
+---
+
+*Keep practicing consistently to see your progress grow!*