Add copy languages command functionality

[konard]

🎯 Summary

This PR implements the ability to copy programming languages from another user's profile using a command, as requested in issue #95.

📋 Issue Reference

Fixes #95

✨ Features Added

• New Command: copy languages / копировать языки
• Functionality: Copy all programming languages from another user's profile to your own profile
• Usage: Send the command as a reply to or forward a message from the user whose languages you want to copy
• Smart Merging: Only adds new languages that you don't already have
• User Feedback: Informative messages about successful copies, duplicates, and edge cases

🔧 Implementation Details

1. Pattern Matching: Added COPY_LANGUAGES regex pattern supporting both English and Russian commands
2. Command Logic: Implemented copy_languages() method in Commands class with comprehensive error handling
3. Documentation: Updated README.md with command description and Russian alias
4. Registration: Integrated the new command into the main bot command registry

🛡️ Edge Case Handling

• ✅ No forwarded message: Prompts user to forward a message
• ✅ Self-copy attempt: Rejects and prompts for different user
• ✅ Source user has no languages: Informs user appropriately
• ✅ All languages already exist: Notifies user of no new additions
• ✅ Partial overlap: Reports only new languages added

🎮 Usage Examples

# English command
copy languages
(reply to or forward someone's message)

# Russian command  
копировать языки
(reply to or forward someone's message)

📝 Testing

• ✅ Regex pattern validation for both English and Russian commands
• ✅ Syntax validation for all modified Python files
• ✅ Import verification for new patterns and methods
• ✅ Edge case logic verification

---

🤖 Generated with Claude Code