feat: loading on login submit

lib/src/providers/auth_provider.dart

@@ -36,9 +36,13 @@ class AuthProvider with ChangeNotifier {
     return await storage.read(key: 'access_token');
   }
 
+  void setLoading(bool value) {
+    isLoading = value;
+  }
+
   Future<void> signIn(String username, String password) async {
-    isLoading = true;
     try {
+      setLoading(true);
       final response = await http.post(
         Uri.parse('$baseUrl/auth/login'),
         body: jsonEncode({'username': username, 'password': password}),
@@ -62,7 +66,7 @@ class AuthProvider with ChangeNotifier {
         debugPrint("Login failed $code");
       }
 
-      isLoading = false;
+      setLoading(false);
       notifyListeners();
     } catch (error) {
       debugPrint("Login failed $error");

lib/src/widgets/forms/login_form.dart

@@ -133,7 +133,16 @@ class _LoginForm extends State<LoginForm> {
                               passwordController.text,
                             );
                           },
-                          child: const Text("Submit"),
+                          child: authProvider.isLoading
+                              ? const SizedBox(
+                                  width: 20.0,
+                                  height: 20.0,
+                                  child: CircularProgressIndicator(
+                                    color: Colors.white,
+                                    strokeWidth: 3.0,
+                                  ),
+                                )
+                              : const Text("Submit"),
                         ),
                       ),
                       SizedBox(