feat: switch to persistent SQLite database and improve GPU booking/release handling

- Change database from in-memory to file-based SQLite at aitbc_coordinator.db
- Add status="active" to GPU booking creation
- Allow GPU release even when not properly booked (cleanup case)
- Add error handling for missing booking attributes during refund calculation
- Fix get_gpu_reviews query to use scalars() for proper result handling

apps/coordinator-api/src/app/database.py

@@ -5,7 +5,7 @@ from sqlalchemy import StaticPool
 
 # Create in-memory SQLite database for now
 engine = create_engine(
-    "sqlite:///:memory:",
+    "sqlite:////home/oib/windsurf/aitbc/apps/coordinator-api/aitbc_coordinator.db",
     connect_args={"check_same_thread": False},
     poolclass=StaticPool,
     echo=False