Add end-to-end tests for parent notifications and actions

- Implement tests for approving and denying rewards and chores, including token generation and validation.
- Create tests for error handling scenarios with expired, tampered, and fake tokens.
- Add tests for push subscription registration and user profile notification settings.
- Ensure that notifications reflect the correct state of rewards and chores in the UI.
- Validate that toggles for email digest and push notifications function correctly based on user permissions and server state.

.github/specs/feat-parent-chore-notifications.md

@@ -240,11 +240,11 @@ A full Playwright E2E test plan has been produced and saved to:
 
 `frontend/vue-app/e2e/plans/parent-notifications.plan.md`
 
-The plan covers 9 scenario groups (41 automated test cases + 1 manual QA checklist):
+The plan covers 10 scenario groups (56 automated test cases + 1 manual QA checklist):
 
 | #   | Group                                     | Cases |
 | --- | ----------------------------------------- | ----- |
-| 1   | Push subscription registration            | 5     |
+| 1   | Push subscription registration            | 3     |
 | 2   | Chore notification — approve flow         | 8     |
 | 3   | Chore notification — reject flow          | 5     |
 | 4   | Reward notification — grant flow          | 7     |
@@ -253,6 +253,7 @@ The plan covers 9 scenario groups (41 automated test cases + 1 manual QA checkli
 | 7   | Digest action token — happy paths         | 8     |
 | 8   | Digest action token — error paths         | 5     |
 | 9   | Service Worker push — manual QA checklist | —     |
+| 10  | User Profile notification toggles         | 7     |
 
 **Prerequisite noted in plan:** A backend test-only endpoint `POST /api/admin/test/digest-token` (active only when `DB_ENV=e2e`) is required before scenario groups 7 and 8 can run.