feat(frontend): make baseUrl dynamic for external network access and clear default login inputs

FinlyticApp/lib/features/auth/views/login_screen.dart

@@ -14,8 +14,15 @@ class LoginScreen extends StatefulWidget {
 
 class _LoginScreenState extends State<LoginScreen> {
   final _formKey = GlobalKey<FormState>();
-  final _emailController = TextEditingController(text: 'admin@finlytic.com');
-  final _passwordController = TextEditingController(text: 'AdminDefaultPassword2026!');
+  final _emailController = TextEditingController();
+  final _passwordController = TextEditingController();
+
+  @override
+  void dispose() {
+    _emailController.dispose();
+    _passwordController.dispose();
+    super.dispose();
+  }
 
   void _onLogin() {
     if (_formKey.currentState?.validate() ?? false) {

FinlyticApp/lib/features/dashboard/widgets/daily_news_snapshot.dart

@@ -14,19 +14,19 @@ import '../../news/widgets/article_sentiment_dialog.dart';
 
 class DailyNewsSnapshot extends StatelessWidget {
   final ApiClient apiClient;
-  final String backendUrl;
+  final String? backendUrl;
 
   const DailyNewsSnapshot({
     super.key,
     required this.apiClient,
-    this.backendUrl = 'http://localhost:5000',
+    this.backendUrl,
   });
 
   @override
   Widget build(BuildContext context) {
     return BlocProvider(
       create: (context) => NewsBloc(
-        repository: NewsRepository(apiClient: apiClient, backendUrl: backendUrl),
+        repository: NewsRepository(apiClient: apiClient, backendUrl: backendUrl ?? ApiClient.baseUrl),
       )..add(FetchNews(date: DateTime.now().toIso8601String().substring(0, 10))),
       child: const _DailyNewsSnapshotContent(),
     );