fix: add pool_pre_ping and pool_recycle to prevent stale Neon connection errors

app/services/database.py

@@ -17,7 +17,11 @@ if "localhost" not in DATABASE_URL and "sslmode" not in DATABASE_URL:
     else:
         DATABASE_URL += "?sslmode=require"
         
-engine= create_engine(DATABASE_URL)
+engine = create_engine(
+    DATABASE_URL,
+    pool_pre_ping=True,   # Test connection health before use; silently replaces dead connections
+    pool_recycle=300,     # Recycle connections every 5 min, before Neon's idle timeout closes them
+)
 SessionLocal= sessionmaker(autocommit= False, autoflush= False, bind= engine)
 Base= declarative_base()