- Added `marked_for_deletion` and `marked_for_deletion_at` fields to User model (Python and TypeScript) with serialization updates
- Created POST /api/user/mark-for-deletion endpoint with JWT auth, error handling, and SSE event trigger
- Blocked login and password reset for marked users; added new error codes ACCOUNT_MARKED_FOR_DELETION and ALREADY_MARKED
- Updated UserProfile.vue with "Delete My Account" button, confirmation modal (email input), loading state, success/error modals, and sign-out/redirect logic
- Synced error codes and model fields between backend and frontend
- Added and updated backend and frontend tests to cover all flows and edge cases
- All Acceptance Criteria from the spec are complete and verified
- Implemented logic to hide delete button for system tasks and rewards in ItemList.vue, TaskView.vue, and RewardView.vue.
- Added backend checks in task_api.py and reward_api.py to return 403 for delete requests on system items.
- Ensured that items without a user_id are treated as system items across frontend and backend.
- Updated acceptance criteria to include UI and backend tests for the new functionality.
