支持添加删除服务器信息，以在服务器状态页显示CPU、内存等

lib/data/store/server.dart

@@ -1 +1,27 @@
+import 'dart:convert';
 
+import 'package:toolbox/core/persistant_store.dart';
+import 'package:toolbox/data/model/server_private_info.dart';
+
+class ServerStore extends PersistentStore {
+  void put(ServerPrivateInfo info) {
+    final ss = fetch();
+    if (!have(info)) ss.add(info);
+    box.put('servers', json.encode(ss));
+  }
+
+  List<ServerPrivateInfo> fetch() {
+    return getServerInfoList(
+        json.decode(box.get('servers', defaultValue: '[]')!))!;
+  }
+
+  void delete(ServerPrivateInfo s) {
+    final ss = fetch();
+    ss.removeWhere((e) => e.ip == s.ip && e.port == s.port && e.user == e.user);
+    box.put('servers', json.encode(ss));
+  }
+
+  bool have(ServerPrivateInfo s) => fetch()
+      .where((e) => e.ip == s.ip && e.port == s.port && e.user == e.user)
+      .isNotEmpty;
+}