feat(sidebar): 文件页与文件变动页 UIUX 重构 + 全局组件抽取

文件页（FileTree/TreePanel）
- Ctrl/Cmd 多选 + Shift 按可见行序连选（Esc/点空白/右键收敛），批量条支持复制路径、批量删除（共享 ConfirmDialog + 顺序 fsRemove）
- Git 变更着色：行名按状态上色 + M/A/D/U 徽标，目录按 dirHasChanges 着色，非仓库静默降级（数据来自共享 git 状态存储）
- 新建文件夹：fs.mkdir 路由 + mkdirWorkspaceEntry + 内联输入行（Enter/Esc/blur/IME 守卫）
- 性能：FileRow/DirRow memo（含反向验证）、搜索 hidden 停车不再卸载树、level 拉取世代守卫 + AbortController、fs.tree truncated 提示、use-dir-watch 入参 memo
- 拖拽上传视觉 token 化（硬编码色清零）；可见性下传后隐藏页签停止轮询
- 右键「打开方式」改为复用 DSH 自带 open-in-app（宿主探测的关联应用 + 文件管理器显示）

文件变动页（changes/diff）
- 36px 头（宿主 SegmentedControl）+ 单一 ChangeRow + SectionHeader 分组 + 吸底提交条单状态行 + 历史独立空态
- 修掉：双份空态、暂存失败 unhandled rejection、手动刷新被丢、仓库切换刷新两次、worktree 清单缺 repoRoot、工作树被自动切走、预览持旧快照、恢复高度未 clamp、session ops 无谓轮询
- DiffPane/DiffTab 共用 use-git-diff；修掉 DiffPane 的 untracked 预览从不渲染

全局组件与宿主接入
- 新增 src/client/ui（IconButton/Chip/SectionHeader/Notice/ConfirmDialog/StatusBadge + 共享 git 状态存储）
- 新增 src/client/open-in-app.ts（宿主 open-in-app 客户端适配），删除自研 open-with 全链路与 open.external 路由
- 客户端 inject 补 remote / remote.session：缺声明时 ctx.get('remote').session 会抛出并把整个面板打成错误条（真实挂载 lane 抓到）
- 词典：+25 键 / -20 openWith* / -noChanges，20 份同步

验证：typecheck / lint / test（126 文件 1322 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（含 tab sweep 与 perf lane）

src/client/use-dir-watch.ts

@@ -13,7 +13,7 @@
  * that one cached level and re-lists it. Folders the reader collapsed are
  * un-watched, so a long session does not accumulate handles.
  */
-import { useEffect, useRef } from 'react'
+import { useEffect, useMemo, useRef } from 'react'
 
 /** One server frame: a stale directory, a watch verdict, or a refusal. */
 interface FsWatchFrame {
@@ -47,15 +47,23 @@ const RETRY_MAX_MS = 15_000
 export function useDirectoryWatch(options: DirectoryWatchOptions): void {
   const { sessionId, root, dirs, onStale } = options
   // The expanded set is a fresh array on every render, so neither the socket
-  // effect nor the staleness callback may depend on their identity.
-  const wantedRef = useRef<string[]>([])
-  wantedRef.current = root === undefined ? [...dirs] : [root, ...dirs]
+  // effect nor the staleness callback may depend on their identity. The
+  // CONTENT key (NUL-joined paths — no path can contain one) is what the
+  // arrays are derived from, so a re-render with the same expanded set
+  // rebuilds neither the wanted list nor the effect dependency.
+  const dirsKey = dirs.join('\u0000')
+  const wanted = useMemo(() => {
+    const listed = dirsKey === '' ? [] : dirsKey.split('\u0000')
+    return root === undefined ? listed : [root, ...listed]
+  }, [root, dirsKey])
+  const wantedRef = useRef(wanted)
+  wantedRef.current = wanted
   const staleRef = useRef(onStale)
   staleRef.current = onStale
   /** Set by the socket effect; reconciles the host's watch set with the tree's. */
   const reconcileRef = useRef<() => void>(() => {})
   // One string per expanded-set change: a stable dependency for the effect below.
-  const wantedKey = wantedRef.current.join('\u0000')
+  const wantedKey = useMemo(() => wanted.join('\u0000'), [wanted])
 
   useEffect(() => {
     if (sessionId === undefined) return