Create User model Models/User.swift, Models/UserRepository.swift User, UserRepository REQUIREMENTS.md § R1, TECH-SPEC.md § AD-1 none Create User struct with Codable conformance. Implement UserRepository with GRDB persistence. Follow offline-first pattern from TECH-SPEC.md. Unit test: UserRepositoryTests — insert, fetch, delete pass User model persists to local DB with full CRUD Create login endpoint Services/AuthService.swift, ViewModels/LoginViewModel.swift AuthService, LoginViewModel REQUIREMENTS.md § R2 Create User model Use Firebase Auth for authentication. Store session in Keychain per TECH-SPEC.md § Security. Handle offline: queue login attempt, retry on connectivity. Login with test credentials returns valid session token User can log in; session persists across app restarts Configure Firebase project GoogleService-Info.plist TECH-SPEC.md § Tech Stack none User must: 1. Create Firebase project at console.firebase.google.com 2. Download GoogleService-Info.plist 3. Add to Xcode project root FirebaseApp.configure() succeeds without crash Firebase SDK initialized on app launch