feat: Initialize Flutter app with authentication and scheduling features

- Removed TypeScript configuration file (tsconfig.json).
- Added Flutter plugin dependencies for secure storage.
- Implemented main application structure with routing for login, profile, and schedule screens.
- Developed LoginScreen with authentication logic and user feedback.
- Created ProfileScreen to display user profile information and logout functionality.
- Built ScheduleScreen to show weekly work schedule with navigation controls.
- Integrated AuthService for handling authentication, token storage, and API interactions.
- Updated pubspec.yaml with necessary dependencies for the Flutter project.

pubspec.yaml

@@ -0,0 +1,21 @@
+name: iso_flutter_app
+description: Minimal Flutter port of the React Native app (login, profile, weekly schedule)
+publish_to: 'none'
+version: 0.0.1
+environment:
+  sdk: ">=2.18.0 <3.0.0"
+
+dependencies:
+  flutter:
+    sdk: flutter
+  http: ^0.13.6
+  flutter_secure_storage: ^8.0.0
+  provider: ^6.0.5
+  intl: ^0.18.0
+
+dev_dependencies:
+  flutter_test:
+    sdk: flutter
+
+flutter:
+  uses-material-design: true