Integrate ApiSettingsViewModel into main.dart

Updated main.dart to provide ApiSettingsViewModel at the top-level using MultiProvider. This ensures that the ViewModel is accessible throughout the app, allowing for dynamic updates to the API's base URL.

lib/main.dart

@@ -1,3 +1,4 @@
+import 'package:auto_gpt_flutter_client/viewmodels/api_settings_viewmodel.dart';
 import 'package:flutter/material.dart';
 import 'views/main_layout.dart';
 import 'package:provider/provider.dart';
@@ -42,6 +43,7 @@ class MyApp extends StatelessWidget {
               create: (context) => ChatViewModel(chatService)),
           ChangeNotifierProvider(
               create: (context) => TaskViewModel(taskService)),
+          ChangeNotifierProvider(create: (context) => ApiSettingsViewModel()),
         ],
         child: const MainLayout(),
       ), // Set MainLayout as the home screen of the app