Fix SQLAlchemy RuntimeError in integration tests

- Remove db.init_app() call causing 'already registered' error
- Use db.engine.dispose() to clear existing engine
- Use db.session.remove() to clean up sessions
- Forces new connection with in-memory database config
- Fixes 10 failing tests in test_app_activity_functions.py

tests/integration/test_app_activity_functions.py

@@ -35,6 +35,9 @@ class TestFlaskAppActivityFunctions(unittest.TestCase):
         # Store original database URI
         self.original_db_uri = app.app.config.get("SQLALCHEMY_DATABASE_URI")
 
+        # Store original db engine
+        self.original_db_engine = db.engine if hasattr(db, 'engine') else None
+
         # Configure test app BEFORE pushing context
         app.app.config["TESTING"] = True
         app.app.config["SQLALCHEMY_DATABASE_URI"] = "sqlite:///:memory:"
@@ -47,8 +50,11 @@ class TestFlaskAppActivityFunctions(unittest.TestCase):
         self.app_context = app.app.app_context()
         self.app_context.push()
 
-        # Reinitialize db with the test app to pick up new config
-        db.init_app(app.app)
+        # Force db to use the new in-memory database by clearing the engine
+        # This allows the in-memory database to be created
+        if hasattr(db, 'engine'):
+            db.engine.dispose()
+        db.session.remove()
 
         # Re-initialize db with test config to use in-memory database
         try: