feat(w5): ship v2.0.0 platform sync, undo persistence, and updates

Co-authored-by: Cursor <cursoragent@cursor.com>

public/locales/zh-CN/translation.json

@@ -589,5 +589,50 @@
   "readMode.fontSerif": "衬线",
   "readMode.fontSans": "无衬线",
   "readMode.fontEyeCare": "护眼",
-  "readMode.tts": "朗读"
+  "readMode.tts": "朗读",
+  "settings.extensions": "扩展",
+  "sync.title": "云同步",
+  "sync.desc": "将加密后的全部书籍备份同步到 WebDAV 或本地云盘目录",
+  "sync.mode": "同步方式",
+  "sync.modeLocal": "本地目录",
+  "sync.modeWebdav": "WebDAV",
+  "sync.localPathPlaceholder": "选择或输入同步目录路径",
+  "sync.pickFolder": "选择目录",
+  "sync.webdavUrl": "WebDAV 地址",
+  "sync.webdavUser": "WebDAV 用户名",
+  "sync.schedule": "同步计划",
+  "sync.scheduleManual": "手动",
+  "sync.scheduleHourly": "每小时",
+  "sync.scheduleDaily": "每天",
+  "sync.scheduleWeekly": "每周",
+  "sync.passwordPlaceholder": "同步密码（至少 8 位）",
+  "sync.passwordHint": "请设置至少 8 位的同步密码",
+  "sync.saveConfig": "保存同步配置",
+  "sync.runNow": "立即同步",
+  "sync.running": "同步中…",
+  "sync.done": "同步完成",
+  "sync.configSaved": "同步配置已保存",
+  "sync.lastSync": "上次同步：{{time}}（{{status}}）",
+  "sync.conflictTitle": "同步冲突",
+  "sync.conflictDesc": "本地与远程均有更新，请选择保留哪一侧的数据。",
+  "sync.useRemote": "使用远程",
+  "sync.useLocal": "使用本地",
+  "extensions.title": "扩展",
+  "extensions.desc": "扩展 API 骨架（不执行第三方代码）",
+  "extensions.devMode": "开发者模式（仅校验 manifest）",
+  "extensions.stubHint": "完整插件市场将在后续版本提供。",
+  "update.available": "新版本 {{version}} 可用",
+  "update.download": "下载更新",
+  "update.downloading": "下载中 {{percent}}%",
+  "update.install": "重启并安装",
+  "crash.title": "检测到异常退出",
+  "crash.desc": "上次使用时应用可能异常退出。可发送本地日志报告（当前为 stub）。",
+  "crash.send": "发送报告",
+  "crash.dismiss": "忽略",
+  "ai.settings.builtinSkills": "内置 Skill",
+  "ai.settings.skillContinue": "续写助手",
+  "ai.settings.skillPolish": "润色助手",
+  "ai.settings.skillProofread": "纠错助手",
+  "ai.settings.mcpConnector": "MCP 连接器 URL",
+  "ai.settings.mcpTest": "测试连接"
 }