Implement chat-specific karma system

[konard]

🎯 Summary

This PR implements a chat-specific karma system to address issue #8 "Should the rating be splited in different chats?".

Previously, the VK bot used a global karma system where users had a single karma score across all chats. Now users have separate karma scores for each chat, making ratings truly chat-specific.

🔧 Key Changes

Data Structure Migration

• Before: karma: 10 (global integer)
• After: karma: {2000000001: 10, 2000000002: -2} (per-chat dictionary)

Same approach applied to supporters and opponents arrays.

Core Features

• ✅ Chat-specific karma: Each user has separate karma per chat
• ✅ Isolated voting: Votes in one chat don't affect karma in other chats
• ✅ Chat-specific rankings: Top lists show karma specific to current chat
• ✅ Backward compatibility: Existing global karma data migrates automatically
• ✅ Seamless transition: Old and new formats work during migration

Modified Files

• python/modules/data_service.py: Added chat-specific karma/supporters/opponents methods
• python/modules/data_builder.py: Updated karma calculations for chat-specific data
• python/modules/commands_builder.py: Updated message builders to use chat-specific karma
• python/modules/commands.py: Updated karma commands to use chat-specific data

🧪 Testing

• ✅ Implementation logic validated with test scripts
• ✅ Python syntax verified across all modified files
• ✅ Backward compatibility confirmed for existing data
• ✅ Migration path tested for old integer karma format

🔄 Migration Strategy

The implementation automatically handles migration:

1. New users: Start with empty karma dictionaries
2. Existing users with zero karma: Migrate to empty dictionary
3. Existing users with karma: Migrate integer to {current_chat: karma_value}
4. Mixed scenarios: Support both formats during transition

📋 Examples

Before (Global Karma)

User A: karma=10 everywhere
Chat 1 ranking: User A [10]
Chat 2 ranking: User A [10]  

After (Chat-Specific Karma)

User A: karma={chat1: 15, chat2: -3}
Chat 1 ranking: User A [15]
Chat 2 ranking: User A [-3]

✅ Answer to Issue #8

Question: "Should the rating be splited in different chats?"
Answer: YES - This PR implements exactly that! Ratings are now split across different chats, giving users separate karma scores per chat.

---

🤖 Generated with Claude Code

---

Resolves #8