优化备份逻辑，连同头像一起备份

lib/widgets/movie_list_item.dart

@@ -133,23 +133,50 @@ class MovieListItem extends StatelessWidget {
       builder: (context) => AlertDialog(
         backgroundColor: Colors.white,
         elevation: 0,
-        shape: const RoundedRectangleBorder(borderRadius: BorderRadius.zero),
-        title: const Text('确认删除'),
-        content: Text('确定要删除《${movie.title}》吗？'),
+        shape: RoundedRectangleBorder(borderRadius: BorderRadius.circular(12)),
+        title: const Text(
+          '确认删除',
+          style: TextStyle(
+            fontSize: 18,
+            fontWeight: FontWeight.w600,
+          ),
+        ),
+        content: Text(
+          '确定要删除《${movie.title}》吗？删除后可在回收站恢复。',
+          style: const TextStyle(
+            fontSize: 14,
+            color: Color(0xFF666666),
+            height: 1.5,
+          ),
+        ),
         actions: [
           TextButton(
             onPressed: () => Navigator.pop(context),
-            child: const Text('取消', style: TextStyle(color: Color(0xFF666666))),
+            style: TextButton.styleFrom(
+              foregroundColor: const Color(0xFF666666),
+              padding: const EdgeInsets.symmetric(horizontal: 16, vertical: 8),
+            ),
+            child: const Text('取消'),
           ),
-          TextButton(
+          ElevatedButton(
             onPressed: () async {
               await context.read<AppProvider>().removeMovie(movie.id);
               Navigator.pop(context);
               ToastUtil.show(context, '已删除');
             },
-            child: const Text('删除', style: TextStyle(color: Colors.red)),
+            style: ElevatedButton.styleFrom(
+              backgroundColor: Colors.red,
+              foregroundColor: Colors.white,
+              elevation: 0,
+              shape: RoundedRectangleBorder(
+                borderRadius: BorderRadius.circular(8),
+              ),
+              padding: const EdgeInsets.symmetric(horizontal: 16, vertical: 8),
+            ),
+            child: const Text('删除'),
           ),
         ],
+        actionsPadding: const EdgeInsets.symmetric(horizontal: 16, vertical: 12),
       ),
     );
   }