Enhance Customer model to include role attribute and update related components

- Added a new `role` attribute to the `Customer` model in `customer.dart` and updated the corresponding generated files.
- Modified the `AuthViewModel` to set the user role based on the logged-in user's role.
- Updated UI components in `TenderDetailActions` and `DesktopTendersPage` to conditionally render elements based on the user's role.
- Refactored tests to validate the new role attribute in the `Customer` model.

lib/view_models/auth_view_model.dart

@@ -33,11 +33,13 @@ class AuthViewModel with ChangeNotifier {
   String? _errorMessage;
   Customer? _loggedInUser;
   String? successMessage;
+  Role? _userRole;
 
   bool get isLoading => _isLoading;
   bool get isLoggedIn => _isLoggedIn;
   String? get errorMessage => _errorMessage;
   Customer? get loggedInUser => _loggedInUser;
+  Role? get userRole => _userRole;
 
   void togglePasswordVisibility() {
     _obscurePassword = !_obscurePassword;
@@ -63,6 +65,7 @@ class AuthViewModel with ChangeNotifier {
     switch (result) {
       case Ok<LoginResponseModel>():
         _loggedInUser = result.value.data.customer;
+        _userRole = _loggedInUser?.role == 'admin' ? Role.admin : Role.analyst;
         usernameController.clear();
         passwordController.clear();
         break;
@@ -123,3 +126,5 @@ class AuthViewModel with ChangeNotifier {
     super.dispose();
   }
 }
+
+enum Role { admin, analyst }