fix: improve maintenance and synchronize live conversations

backend/app/main.py

@@ -29,18 +29,17 @@ from app.api import channels as channels_api
 from app.api import webhooks as channel_webhooks
 # Import widget_chat to register socket.io event handlers for /widget namespace
 from app.api import widget_chat  # noqa: F401 - imported for side effects (socket.io handlers registration)
-from fastapi import FastAPI, BackgroundTasks
+from fastapi import FastAPI
 from app.core.config import settings, verify_secret_configuration
 from app.core.encryption import verify_encryption_key
 from app.services.file_storage import PUBLIC_UPLOAD_FOLDERS
 from app.services.firebase import initialize_firebase
-from app.database import engine, Base
 import asyncio
 from app.core.logger import get_logger
 from contextlib import asynccontextmanager
 import os
 from app.channels.app_hooks import load_extensions
-from app.core.socketio import socket_app, configure_socketio, sio
+from app.core.socketio import configure_socketio, sio
 from app.core.cors import (
     FirstPartyCredentialsCORSMiddleware,
     first_party_origins,
@@ -51,10 +50,10 @@ from app.core.cors import (
 from app.core.application import app, initialize_cors_listener
 from app.core.crawler_policy import install_crawler_policy
 
-# Import models to ensure they're registered with SQLAlchemy
-from app.models import Organization, User, Customer
+# Import the model package so every mapped class is registered with SQLAlchemy.
+import app.models as _models  # noqa: F401 - SQLAlchemy mapper registration side effect.
 try:
-    from app.enterprise.models import OTP
+    from app.enterprise.models import OTP  # noqa: F401 - importing registers optional enterprise ORM models
 except ImportError:
     print("Enterprise models not available")
 from app.api import session_to_agent