feat(flutter): 增加目录加载诊断与前台重试

lib/core/widgets/empty_state.dart

@@ -25,6 +25,7 @@ class EmptyState extends StatelessWidget {
     this.actionLabel,
     this.actionKey,
     this.onAction,
+    this.footer,
     this.compact = false,
   });
 
@@ -34,6 +35,7 @@ class EmptyState extends StatelessWidget {
   final String? actionLabel;
   final Key? actionKey;
   final VoidCallback? onAction;
+  final Widget? footer;
   final bool compact;
 
   @override
@@ -65,6 +67,7 @@ class EmptyState extends StatelessWidget {
                   actionLabel: hasAction ? actionLabel : null,
                   actionKey: actionKey,
                   onAction: hasAction ? onAction : null,
+                  footer: footer,
                 ),
               ],
             ),
@@ -101,6 +104,7 @@ class _EmptyCopy extends StatelessWidget {
     required this.actionLabel,
     required this.actionKey,
     required this.onAction,
+    required this.footer,
   });
 
   final String title;
@@ -108,6 +112,7 @@ class _EmptyCopy extends StatelessWidget {
   final String? actionLabel;
   final Key? actionKey;
   final VoidCallback? onAction;
+  final Widget? footer;
 
   @override
   Widget build(BuildContext context) {
@@ -162,6 +167,7 @@ class _EmptyCopy extends StatelessWidget {
             ),
           ),
         ],
+        if (footer != null) ...[const SizedBox(height: 12), footer!],
       ],
     );
   }