refactored HTTP error handling and streamlined UI components by centralizing shared logic and removing redundant parameters

lib/widget/async_actions/async_dialog_action.dart

@@ -5,14 +5,12 @@ class AsyncDialogAction extends StatefulWidget {
   final AsyncActionCallback onConfirm;
   final String? cancelLabel;
   final AsyncErrorBuilder? errorBuilder;
-  final ButtonStyle? confirmStyle;
 
   const AsyncDialogAction({
     required this.confirmLabel,
     required this.onConfirm,
     this.cancelLabel = 'Abbrechen',
     this.errorBuilder,
-    this.confirmStyle,
     super.key,
   });
 
@@ -58,7 +56,6 @@ class _AsyncDialogActionState extends State<AsyncDialogAction> {
                   child: Text(widget.cancelLabel!),
                 ),
               TextButton(
-                style: widget.confirmStyle,
                 onPressed: _controller.busy
                     ? null
                     : () async {