feat(redis): refactor Redis configuration to use multiple logical databases

- Updated default REDIS_URL to remove explicit /0 suffix
- Added dedicated Redis clients:
  - db0: general cache (redis_client)
  - db1: message cache (redis_message_client)
  - db2: binary storage (redis_binary_client)
  - db3: rate limiting (redis_rate_limit_client)
- Updated configuration, Docker files, and main startup lifecycle accordingly
- Replaced `get_redis()` usage in notification server with `redis_message_client`

app/config.py

@@ -141,7 +141,7 @@ STORAGE_SETTINGS='{
     ]
     redis_url: Annotated[
         str,
-        Field(default="redis://127.0.0.1:6379/0", description="Redis 连接 URL"),
+        Field(default="redis://127.0.0.1:6379", description="Redis 连接 URL"),
         "数据库设置",
     ]