feat: explore tab, React Query data layer, programs, sync, analytics, testing infrastructure

- Replace browse tab with Supabase-connected explore tab with filters
- Add React Query for data fetching with loading states
- Add 3 structured programs with weekly progression
- Add Supabase anonymous auth sync service
- Add PostHog analytics with screen tracking and events
- Add comprehensive test strategy (Vitest + Maestro E2E)
- Add RevenueCat subscription system with DEV simulation
- Add i18n translations for new screens (EN/FR/DE/ES)
- Add data deletion modal, sync consent modal
- Add assessment screen and program routes
- Add GitHub Actions CI workflow
- Update activity store with sync integration

AGENTS.md

@@ -305,13 +305,39 @@ const queryClient = new QueryClient({
 # TypeScript
 npx tsc --noEmit
 
-# Run tests
+# Run unit tests (Vitest)
 npm test
 
+# Run tests in watch mode
+npm run test:watch
+
+# Run tests with coverage report
+npm run test:coverage
+
+# Run Maestro E2E tests
+npm run test:maestro
+
 # Lint
 npx eslint .
 ```
 
+#### Test Structure
+```
+src/__tests__/
+  setup.ts              # Mocks and test configuration
+  stores/               # Zustand store tests
+  hooks/                # React hooks tests
+  services/             # Service layer tests
+  components/           # Component logic tests
+  data/                 # Data validation tests
+```
+
+#### Coverage Goals
+- **Stores**: 80%+ (business logic)
+- **Services**: 80%+ (API integration)
+- **Hooks**: 70%+ (timer, purchases)
+- **Components**: 50%+ (critical UI)
+
 ### Key Takeaways
 
 1. **Start simple**: Always test in Expo Go before creating custom builds