Fix database migration import path issue

Updated migrations/env.py to import Base from app.database.session
instead of app.models, fixing the 'cannot import name Base' error.

migrations/env.py

@@ -25,7 +25,9 @@ for container_path in container_paths:
 # Now we can import our application modules
 try:
     from app.core.config import settings  # noqa: F401 - Used in later operations
-    from app.models import Base
+
+    # Import Base from database.session where it's defined
+    from app.database.session import Base
 except ImportError as e:
     print(f"Error importing app modules: {e}")
     print(f"Current sys.path: {sys.path}")