feat(search): add unified global search for users/chats/messages

app/main.py

@@ -13,6 +13,7 @@ from app.media.router import router as media_router
 from app.messages.router import router as messages_router
 from app.notifications.router import router as notifications_router
 from app.realtime.router import router as realtime_router
+from app.search.router import router as search_router
 from app.realtime.service import realtime_gateway
 from app.users.router import router as users_router
 from app.utils.redis_client import close_redis_client, get_redis_client
@@ -74,3 +75,4 @@ app.include_router(messages_router, prefix=settings.api_v1_prefix)
 app.include_router(media_router, prefix=settings.api_v1_prefix)
 app.include_router(notifications_router, prefix=settings.api_v1_prefix)
 app.include_router(realtime_router, prefix=settings.api_v1_prefix)
+app.include_router(search_router, prefix=settings.api_v1_prefix)