Migrate Angular contacts app to React TypeScript

[staging-devin-ai-integration]

Summary

Complete migration of the contacts application from Angular 5 to React 18 with TypeScript. The app maintains all original functionality while using a modern tech stack:

• Angular 5 → React 18 with functional components and hooks
• Angular CLI → Vite for fast builds and HMR
• Karma/Jasmine → Vitest + React Testing Library for testing
• Angular Material → MUI v5 for Material Design components
• Angular Router → React Router v6 for routing
• RxJS observables → simple async/await patterns
• Angular pipes/directives → React components/utility functions

All original features preserved:

• Contact list with CRUD operations
• Contact detail view with feed dialog
• Contact edit with validation (email, phone)
• New contact creation
• Favorite icon with hover states
• Phone number formatting (default, dots, hyphens, with country code)
• Snackbar notifications
• Loading/deleting states

Review & Testing Checklist for Human

• Run cd website && npm install && npm test — all 26 tests should pass
• Run npm run dev and verify the contacts list loads with 4 contacts
• Click a contact to view details, verify phone number formatting
• Edit a contact — test email/phone validation dialogs trigger for invalid input
• Add a new contact and verify it appears in the list
• Delete a contact and verify snackbar notification
• Test the "Delete All Contacts" → "Add Contacts" flow
• Verify the feed dialog opens from contact detail and shows streaming updates

Notes

• The in-memory data service replaces angular-in-memory-web-api with a simple module-level store
• The ShowContactsDirective structural directive was replaced with standard conditional rendering
• The FavoriteIconDirective was converted to a FavoriteIcon React component with hover state management via useState
• Font Awesome and Material Icons CDN links are preserved in index.html

Link to Devin session: https://localhost:3003/sessions/b9256ee5e6cf46a582b08ac41a894f37
Requested by: @lburgers

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[staging-devin-ai-integration]

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