feat: 下载时若存在数据丢失风险则弹窗提示；服务端增加占用信息查看功能

client/lib/dialog.dart

@@ -104,13 +104,13 @@ class _AppConfigDialogState extends State<AppConfigDialog> {
           Row(
             mainAxisAlignment: MainAxisAlignment.spaceEvenly,
             children: [
-              FilledButton(
+              ElevatedButton(
                 onPressed: () {
                   Navigator.of(context).pop();
                 },
                 child: Text('取消'),
               ),
-              ElevatedButton(
+              FilledButton(
                 onPressed: () {
                   var client = clientCtl.text.trim();
                   var server = serverCtl.text.trim();
@@ -223,12 +223,10 @@ class _AddSyncItemDialogState extends State<AddSyncItemDialog> {
             children: [
               IconButton(
                 onPressed: () {
-                  FilePicker.pickFiles(
-                    allowMultiple: false,
-                  ).then(
+                  FilePicker.pickFile().then(
                     (res) {
-                      if (res?.files.firstOrNull?.path?.isNotEmpty == true) {
-                        pathCtl.text = res!.files.first.path!;
+                      if (res?.xFile.path?.isNotEmpty == true) {
+                        pathCtl.text = res!.xFile.path!;
                       }
                     },
                   );
@@ -253,13 +251,13 @@ class _AddSyncItemDialogState extends State<AddSyncItemDialog> {
           Row(
             mainAxisAlignment: MainAxisAlignment.spaceEvenly,
             children: [
-              FilledButton(
+              ElevatedButton(
                 onPressed: () {
                   Navigator.of(context).pop();
                 },
                 child: Text('取消'),
               ),
-              ElevatedButton(
+              FilledButton(
                 onPressed: () {
                   var name = nameCtl.text.trim();
                   var path = pathCtl.text.trim();
@@ -284,3 +282,69 @@ class _AddSyncItemDialogState extends State<AddSyncItemDialog> {
     );
   }
 }
+
+class UploadConfirmDialog extends StatelessWidget {
+  const UploadConfirmDialog({super.key});
+
+  static Future<bool?> show(BuildContext context, [SyncItemConfig? config]) {
+    return showDialog(
+      context: context,
+      builder: (context) => Dialog(
+        child: UploadConfirmDialog(),
+      ),
+    );
+  }
+
+  @override
+  Widget build(BuildContext context) {
+    return Container(
+      width: 400,
+      height: 200,
+      padding: EdgeInsets.all(16),
+      decoration: BoxDecoration(
+        borderRadius: BorderRadius.circular(16),
+        color: Colors.white,
+        boxShadow: [
+          BoxShadow(
+            color: Colors.black26,
+            offset: Offset(4, 4),
+            spreadRadius: 8,
+            blurRadius: 16,
+          ),
+        ],
+      ),
+      child: Column(
+        crossAxisAlignment: CrossAxisAlignment.center,
+        children: [
+          Text(
+            '确认下载并覆盖本地数据？',
+            style: TextStyle(fontSize: 24, fontWeight: FontWeight.bold),
+          ),
+          SizedBox(height: 26),
+          Text(
+            '本地资源修改时间似乎晚于云端\n确认覆盖可能造成数据丢失！',
+            textAlign: TextAlign.center,
+          ),
+          const Spacer(),
+          Row(
+            mainAxisAlignment: MainAxisAlignment.spaceEvenly,
+            children: [
+              ElevatedButton(
+                onPressed: () {
+                  Navigator.of(context).pop(false);
+                },
+                child: Text('取消'),
+              ),
+              FilledButton(
+                onPressed: () {
+                  Navigator.of(context).pop(true);
+                },
+                child: Text('确认'),
+              ),
+            ],
+          ),
+        ],
+      ),
+    );
+  }
+}