Add push notification functionality with tests and digest scheduler

- Implemented push subscription API with tests for subscribing and unsubscribing users.
- Created web push notification tests triggered by child actions.
- Added digest scheduler to send email digests to users at 9 PM local time.
- Developed utility functions for creating and validating digest action tokens.
- Integrated web push sender to handle sending notifications to users.
- Added service worker for handling push notifications in the frontend.
- Created a push opt-in component for user notification preferences.
- Implemented tests for the push opt-in component to ensure correct behavior.
- Updated frontend services to manage push subscriptions and permissions.

frontend/vue-app/src/router/__tests__/authGuard.spec.ts

@@ -13,6 +13,7 @@ vi.mock('@/stores/auth', () => ({
   isUserLoggedIn: isUserLoggedInMock,
   isParentAuthenticated: isParentAuthenticatedMock,
   enforceParentExpiry: vi.fn(),
+  setPendingReturnUrl: vi.fn(),
 }))
 
 // Import router AFTER mocks are in place

frontend/vue-app/src/router/index.ts

@@ -29,6 +29,7 @@ import {
   isParentAuthenticated,
   isAuthReady,
   enforceParentExpiry,
+  setPendingReturnUrl,
 } from '../stores/auth'
 import ParentPinSetup from '@/components/auth/ParentPinSetup.vue'
 import LandingPage from '@/components/landing/LandingPage.vue'
@@ -303,6 +304,9 @@ router.beforeEach(async (to, from, next) => {
   if (isParentAuthenticated.value) {
     return next('/parent')
   } else {
+    if (to.path.startsWith('/parent')) {
+      setPendingReturnUrl(to.fullPath)
+    }
     return next('/child')
   }
 })