feat: Complete Phase 1 Authentication and setup Flutter project structure

- Completed authentication system with signup, login, password reset, and logout
- Enhanced error handling and accessibility across all auth flows
- Added comprehensive loading states and user feedback
- Implemented confirmation dialogs for destructive actions
- Setup complete Flutter project structure with proper configuration
- Added planning documentation for Phase 2 household creation
- All Phase 1 success criteria verified and complete

macos/Flutter/GeneratedPluginRegistrant.swift

@@ -0,0 +1,20 @@
+//
+//  Generated file. Do not edit.
+//
+
+import FlutterMacOS
+import Foundation
+
+import app_links
+import flutter_secure_storage_macos
+import path_provider_foundation
+import shared_preferences_foundation
+import url_launcher_macos
+
+func RegisterGeneratedPlugins(registry: FlutterPluginRegistry) {
+  AppLinksMacosPlugin.register(with: registry.registrar(forPlugin: "AppLinksMacosPlugin"))
+  FlutterSecureStoragePlugin.register(with: registry.registrar(forPlugin: "FlutterSecureStoragePlugin"))
+  PathProviderPlugin.register(with: registry.registrar(forPlugin: "PathProviderPlugin"))
+  SharedPreferencesPlugin.register(with: registry.registrar(forPlugin: "SharedPreferencesPlugin"))
+  UrlLauncherPlugin.register(with: registry.registrar(forPlugin: "UrlLauncherPlugin"))
+}