Rework the database migration system

backend/app.py

@@ -1,7 +1,5 @@
 from fastapi import FastAPI
 from fastapi.middleware.cors import CORSMiddleware
-from migration import run_auto_migration
-from db import engine
 
 from routes import account, messaging, profile, push
 
@@ -21,13 +19,4 @@ app.add_middleware(
 app.include_router(account.router)
 app.include_router(messaging.router)
 app.include_router(profile.router)
-app.include_router(push.router, prefix="/push")
-
-
-@app.on_event("startup")
-def _auto_migrate_on_startup():
-    try:
-        run_auto_migration(engine)
-    except Exception:
-        # Keep startup resilient; errors should be visible in server logs
-        pass
+app.include_router(push.router, prefix="/push")