Fix: Add database table initialization on startup

app/main.py

@@ -58,6 +58,10 @@ async def health_check():
 @app.on_event("startup")
 async def startup_event():
     logger.info("Universal Model Trainer starting up...")
+    # Initialize database tables
+    from app.database import init_db
+    await init_db()
+    logger.info("Database tables initialized")
     logger.info("Routers registered: models, datasets, training, system, jobs")
 
 @app.on_event("shutdown")