Update wechat_bot.py with improved error handling, logging, and maintainability

[yashhhYB]

Summary

This PR improves the wechat_bot.py implementation by modernizing the codebase,
adding robust error handling, and aligning with best practices for open-source
contributions.

Key Enhancements

• ✅ Added type hints (Optional, Any, Message) for better IDE support and readability
• ✅ Improved logging with clear levels (info, error, critical, exception) and structured messages
• ✅ Introduced comprehensive error handling with safe fallbacks and sys.exit(1) for fatal errors
• ✅ Added detailed docstrings to all classes and methods
• ✅ Safe attribute access for message sender (getattr)
• ✅ JSON pretty-printing for dictionary responses
• ✅ Graceful shutdown with KeyboardInterrupt handler
• ✅ PEP8 & lint-compliant formatting for clean PR review
• ✅ Consistent initialization flow with fast failure when dependencies are missing

Why This Change?

• Makes the bot easier to maintain and extend
• Prevents silent crashes by surfacing errors clearly
• Provides more informative logs for debugging
• Improves code readability and PR review experience

Testing

• Bot initializes successfully
• Handles valid text messages
• Responds with Second-Me kernel output
• Handles missing Second-Me gracefully
• Shuts down cleanly on Ctrl+C

Next Steps

• Add requirements.txt for dependency management
• Provide an optional Dockerfile for containerized deployment

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This PR is a non-breaking improvement: all existing functionality is preserved,
but with better structure, safety, and maintainability.

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