Refactor code for improved readability and consistency

- Cleaned up whitespace and formatting across multiple files for better readability.

app/database.py

@@ -11,8 +11,8 @@ def init_db(app):
     """Initialize database with Flask app."""
     db.init_app(app)
     migrate.init_app(app, db)
-    
+
     # Import models here to ensure they are registered with SQLAlchemy
     from app.models import user, user_oauth  # noqa: F401
-    
-    return db
+
+    return db