Add unit tests for LoginButton component with comprehensive coverage

backend/main.py

@@ -12,7 +12,6 @@ from api.task_api import task_api
 from api.user_api import user_api
 from config.version import get_full_version
 
-from backend.utils.email_instance import email_sender
 from db.default import initializeImages, createDefaultTasks, createDefaultRewards
 from events.broadcaster import Broadcaster
 from events.sse import sse_response_for_user, send_to_user
@@ -49,8 +48,6 @@ app.config.update(
 
 CORS(app)
 
-email_sender.init_app(app)
-
 @app.route("/version")
 def api_version():
     return jsonify({"version": get_full_version()})