feat. & fix.

- support backup & restore
- fix when client.run empty return

lib/data/model/app/backup.dart

@@ -0,0 +1,52 @@
+import 'package:toolbox/data/model/server/private_key_info.dart';
+import 'package:toolbox/data/model/server/server_private_info.dart';
+import 'package:toolbox/data/model/server/snippet.dart';
+
+class Backup {
+  // backup format version
+  final int version;
+  final String date;
+  final List<ServerPrivateInfo> spis;
+  final List<Snippet> snippets;
+  final List<PrivateKeyInfo> keys;
+  final int primaryColor;
+  final int serverStatusUpdateInterval;
+  final int launchPage;
+
+  Backup(
+    this.version,
+    this.date,
+    this.spis,
+    this.snippets,
+    this.keys,
+    this.primaryColor,
+    this.serverStatusUpdateInterval,
+    this.launchPage,
+  );
+
+  Backup.fromJson(Map<String, dynamic> json)
+      : version = json['version'] as int,
+        date = json['date'],
+        spis = (json['spis'] as List)
+            .map((e) => ServerPrivateInfo.fromJson(e))
+            .toList(),
+        snippets =
+            (json['snippets'] as List).map((e) => Snippet.fromJson(e)).toList(),
+        keys = (json['keys'] as List)
+            .map((e) => PrivateKeyInfo.fromJson(e))
+            .toList(),
+        primaryColor = json['primaryColor'],
+        serverStatusUpdateInterval = json['serverStatusUpdateInterval'],
+        launchPage = json['launchPage'];
+
+  Map<String, dynamic> toJson() => {
+        'version': version,
+        'date': date,
+        'spis': spis,
+        'snippets': snippets,
+        'keys': keys,
+        'primaryColor': primaryColor,
+        'serverStatusUpdateInterval': serverStatusUpdateInterval,
+        'launchPage': launchPage,
+      };
+}