feat(sidebar): 打开方式双源并存 + 多选压缩下载 + 文件变动层级树

用户追加三条需求，全部落地：

1) 打开方式 = 宿主探测应用 + 插件自研 open-with（并存）
- 逐字恢复 src/client/open-with.ts / open-with-settings.tsx / plugin-settings.ts /
  src/open-external.ts / open.external 路由 / api.openExternal / editor descriptor
  的 settings.render，以及 20 个 openWith* 词条（19 份词典从 main 取回原文）
- 恢复 menu-flip.ts + layout.css 子菜单翻转规则（子菜单回来了）
- FileTree 菜单段（无标题行）：宿主行 → 分隔线 → 插件 pinned + 「在应用中打开 >」
  子菜单（图钉 / SSH 后缀原样）→ 分隔线 → 宿主 reveal；宿主可用时过滤插件
  explorer 目标，宿主不可用时插件行照旧（SSH 远端场景保持可用）
- 死键清理：菜单去掉标题行后 openInApp 词条无引用，已从 21 份词典删除

2) 文件页多选右键「压缩并打包下载」
- 新增 src/zip.ts（自研 ZIP：方法 0/8 按收益二选一、UTF-8 bit 11、目录条目、
  自实现 CRC32、无第三方依赖）+ src/archive-route.ts（名净化 + 递归收集）+
  GET /sidebar/archive（同一道 workspace fence、目录递归跳过符号链接、
  10000 条目 / 256 MiB 上限）+ api.archiveUrl
- FileTree：多选 ≥2 项或单选目录时出现；fetch → blob → objectURL 下载，
  路由错误（超限 / fence / 非 GET）以 zipFailed 显示在错误条
- 修掉真实缺陷：central directory 只写 MS-DOS 位而 version-made-by 声称 Unix，
  Info-ZIP 会把每个文件解成 mode 000；改为 Unix 语义（0o100644 * 0x10000，
  << 16 会溢出 int32）。系统 unzip 复验：mode 644/755、unzip -t 无错

3) 文件变动页层级树 + 视觉打磨
- 新增 src/client/changes/change-tree.ts：单子目录链压缩成一行、目录先于文件、
  大小写不敏感排序、文件带 GitFileStatus、目录带下级变更数
- GitLens 两组各自渲染树：折叠状态按「组+路径」独立、默认展开；分组头吸顶 +
  计数胶囊；Stage all/Unstage all 改为带 aria-label 的 IconButton；选中 =
  interactive-bg-active + 2px 内嵌强调条；12px/级缩进 + l1 参考线；
  历史行 hash 徽标 / ref 胶囊 / 作者·时间右对齐

验证：typecheck / lint / test（134 文件 1422 通过）/ build 全绿；
DSH_CMD='npx -y --package @deepseek-ai/dsh@0.1.7-rc.1 dsh' pnpm test:mount 7/7 通过；
真实宿主截图确认三条需求（多选+双源菜单+zip 项、变动页树形层级）

src/client/api.ts

@@ -239,6 +239,51 @@ function gitPayload(scope: SessionScope, worktree: string | undefined, extra: Re
   return scopePayload(scope, { ...(worktree !== undefined && worktree !== '' ? { worktree } : {}), ...extra })
 }
 
+/** One external-open request from the file tree. */
+type OpenExternalPayload =
+  | { action: 'reveal'; path: string }
+  | { action: 'url'; url: string }
+
+/** The host route's success shape. */
+type OpenExternalResult = { started: boolean }
+
+/**
+ * Remote VSCode-family URLs must be consumed on the browser/client machine:
+ * the DSH host can be a headless remote server with no editor or DISPLAY.
+ * Local editor URLs and reveal actions still belong to the host opener.
+ */
+function shouldOpenExternalOnClient(payload: OpenExternalPayload): payload is { action: 'url'; url: string } {
+  if (payload.action !== 'url') return false
+  let parsed: URL
+  try {
+    parsed = new URL(payload.url)
+  } catch {
+    return false
+  }
+  return parsed.protocol !== 'http:'
+    && parsed.protocol !== 'https:'
+    && parsed.hostname === 'vscode-remote'
+    && parsed.pathname.startsWith('/ssh-remote+')
+}
+
+/**
+ * Dispatch an external-open request to the correct machine. SSH remote-editor
+ * URLs stay in the synchronous user-click chain and navigate the client so
+ * its registered vscode:// / cursor:// handler can launch. Everything else
+ * keeps using the DSH host route.
+ */
+function openExternal(payload: OpenExternalPayload): Promise<OpenExternalResult> {
+  if (!shouldOpenExternalOnClient(payload)) {
+    return call<OpenExternalResult>('open.external', payload)
+  }
+  try {
+    window.location.assign(payload.url)
+    return Promise.resolve({ started: true })
+  } catch (error) {
+    return Promise.reject(error)
+  }
+}
+
 /** The sidebar API surface (session scope threaded through every call). */
 export const api = {
   sessionCwd: (scope: SessionScope, signal?: AbortSignal) =>
@@ -377,6 +422,10 @@ export const api = {
       patch,
       ...(expectedRevision !== undefined ? { expectedRevision } : {}),
     }),
+  /** External open for the file tree's "open with" menu. Remote SSH editor
+   *  URLs are launched on the browser/client machine; reveal and local URLs
+   *  keep using the host's platform opener. */
+  openExternal,
 }
 
 /** Absolute URL of the media route for one path (images only). */
@@ -390,6 +439,18 @@ export function downloadUrl(scope: SessionScope, path: string): string {
   return fileUrl(scope, path, true)
 }
 
+/**
+ * Absolute URL of the archive route: one ZIP of every `paths` entry (files
+ * and directories, recursive) served as an attachment. Same GET shape as
+ * {@link downloadUrl}; the repeated `path` parameter is the only difference.
+ */
+export function archiveUrl(scope: SessionScope, paths: readonly string[], name: string): string {
+  const params = new URLSearchParams({ sessionId: scope.sessionId, name })
+  if (scope.cwd !== undefined && scope.cwd !== '') params.set('cwd', scope.cwd)
+  for (const path of paths) params.append('path', path)
+  return `/sidebar/archive?${params.toString()}`
+}
+
 /** Shared URL builder for the /sidebar/file route (media vs download). */
 function fileUrl(scope: SessionScope, path: string, download: boolean): string {
   const params = new URLSearchParams({ sessionId: scope.sessionId, path })