review: fix critical/medium bugs in 4 plugins (round 2)

group_horse_racing:
- settle_race: rewrite with 7 bug fixes (race condition, draw double-credit, empty participants, etc.)
- models.py: reorder fields for correct defaults, add indexes
- message_service: add logger import

danding_points:
- api.py: add finally blocks to 3 methods (add_points, get_history, get_leaderboard)
- database.py: add finally block to get_user_balance

chatai:
- __init__.py: deprecated API→asyncio.to_thread, deduplicate logging, taskkill filter for safety
- screenshot.py: XSS protection with bleach on HTML content
- requirements.txt: add bleach dependency

danding_qqpush:
- api.py L13: fix self-referencing _renderer NameError crash
- api.py: lazy singleton pattern via _get_renderer() instead of per-request ImageRenderer
- __init__.py: mask Token in log output (security)

All 34 tests pass.

danding_bot/plugins/danding_qqpush/__init__.py

@@ -42,7 +42,8 @@ def register_routes():
     routes = create_routes(plugin_config.Token, plugin_config)
     driver.server_app.include_router(routes)
     
-    logger.info(f"[Danding_QqPush] API 路由已注册: /danding/qqpush/{plugin_config.Token}")
+    masked = plugin_config.Token[:4] + "***" if len(plugin_config.Token) > 4 else "***"
+    logger.info(f"[Danding_QqPush] API 路由已注册: /danding/qqpush/{masked}")
 
 
 # 插件加载时注册路由