# Task ID: 21
# Title: Friend System (WeChat Import & Invite)
# Status: pending
# Dependencies: 4, 10, 12
# Priority: medium
# Description: Implement a friend system allowing users to import WeChat friends, view online status, and send game invitations. Include a basic blacklist feature.
# Details:
Frontend: Implement UI for 'Friends List'. Use WeChat API for friend relationship chain authorization and import. Display online/offline status (via WebSocket presence updates). Implement 'Invite to Game' button that generates a shareable link/card. Backend: Store friend relationships. Implement APIs for adding/removing friends and managing blacklists. Use Redis to track online users.

# Test Strategy:
Test WeChat friend import. Verify online status updates in real-time. Send game invitations to friends and confirm they can join the invited room. Test blacklist functionality.