Add callback buttons for top command pagination

[konard]

Summary

This PR adds callback button pagination to the VK bot's top command as requested in issue #124. Users can now navigate through top users using interactive Previous/Next buttons instead of being limited by message size constraints.

🚀 Key Features

• Interactive Pagination: Added Previous/Next callback buttons for navigating through user pages
• Backward Compatibility: Commands with number parameters (e.g., top 15) still work without pagination
• Multiple Command Support: Works with top, bottom, and people commands
• Page Display: Shows current page and total pages (e.g., "2/5")
• Optimized Page Size: 10 users per page for optimal readability

🔧 Technical Implementation

New Components

1. VkKeyboard Class (keyboard_utils.py):

   • Generic VK inline keyboard builder
   • Support for callback and text buttons
   • Chainable API for easy keyboard construction

2. TopPaginationKeyboard Class (keyboard_utils.py):

   • Specialized pagination keyboard for top commands
   • Automatic page calculation and navigation
   • Support for different command types

3. Callback Event Handling:

   • New message_event handler in main Bot class
   • Payload parsing and action routing
   • Error handling with callback acknowledgments

Modified Components

1. Bot Class (__main__.py):

   • Added message_event handler for callback buttons
   • Added send_msg_with_keyboard method
   • Added send_callback_answer method

2. Commands Class (commands.py):

   • Enhanced top method with pagination logic
   • New top_paginated method for paginated display
   • New process_callback and handle_top_pagination methods

📋 Usage Examples

Basic Commands (New Behavior)

• top → Shows first 10 users with pagination buttons
• bottom → Shows first 10 users from bottom with pagination
• people → Shows first 10 users with pagination

Legacy Commands (Unchanged)

• top 15 → Shows exactly 15 users without pagination
• bottom 5 → Shows exactly 5 users from bottom without pagination

Pagination Navigation

Users can click:

• ⬅️ Пред. → Navigate to previous page
• След. ➡️ → Navigate to next page
• Page indicator (e.g., "2/5") → Shows current position (non-functional)

🧪 Test Plan

• Created comprehensive test suite (simple_keyboard_test.py)
• Keyboard JSON generation validation
• Pagination calculation testing
• Interactive demo (demo_callback_buttons.py)
• Backward compatibility verification
• Error handling validation

📊 Benefits

1. Better User Experience: No more message size limitations
2. Easier Navigation: Interactive buttons vs. typing commands
3. Scalability: Works with any number of users
4. Mobile Friendly: Touch-friendly button interface
5. Maintainable: Clean, modular code architecture

Fixes #124

🤖 Generated with Claude Code