Init snippet page and store

lib/data/store/snippet.dart

@@ -0,0 +1,33 @@
+import 'dart:convert';
+
+import 'package:toolbox/core/persistant_store.dart';
+import 'package:toolbox/data/model/server/snippet.dart';
+
+class SnippetStore extends PersistentStore {
+  void put(Snippet snippet) {
+    final ss = fetch();
+    if (!have(snippet)) ss.add(snippet);
+    box.put('snippet', json.encode(ss));
+  }
+
+  List<Snippet> fetch() {
+    return getSnippetList(
+        json.decode(box.get('snippet', defaultValue: '[]')!));
+  }
+
+  void delete(Snippet s) {
+    final ss = fetch();
+    ss.removeAt(index(s));
+    box.put('snippet', json.encode(ss));
+  }
+
+  void update(Snippet old, Snippet newInfo) {
+    final ss = fetch();
+    ss[index(old)] = newInfo;
+    box.put('snippet', json.encode(ss));
+  }
+
+  int index(Snippet s) => fetch().indexWhere((e) => e.name == s.name);
+
+  bool have(Snippet s) => index(s) != -1;
+}