feat: 推荐插件目录收录 dsh-sentinel（Tab 注册）

- plugins-tabs.ts 收录 dsh-sentinel（条件驱动的 agent 唤醒系统，注册 dsh-sentinel:watches Tab）
- install 拼接官方一键命令：cd ~/.dsh && dsh plugin --profile web add "github:fuhefei/dsh-sentinel#v0.7.0"
- 新增 pluginSentinelDesc 文案（zh/en）；测试同步（tab 目录不再为空态）

tests/add-plugin-modal.spec.tsx

@@ -48,11 +48,12 @@ describe('PluginListBody (render)', () => {
     expect(html).toContain('Copy')
   })
 
-  it('tab kind renders its own empty state (no office entry)', () => {
+  it('tab kind renders the sentinel entry (its own catalog, no office entry)', () => {
     const store = createSidebarStore()
     const service = createBetterSidebarService(store)
     const html = renderToString(createElement(PluginListBody, { service, kind: 'tab' }))
-    expect(html).toContain('No plugins curated yet')
+    expect(html).toContain('dsh-sentinel 唤醒系统')
+    expect(html).toContain('github:fuhefei/dsh-sentinel')
     expect(html).not.toContain(officeEntry.name)
   })
 })
@@ -75,7 +76,7 @@ describe('AddPluginModal wiring', () => {
       if (kind === 'viewer') {
         expect(html).toContain(officeEntry.name)
       } else {
-        expect(html).toContain('No plugins curated yet')
+        expect(html).toContain('dsh-sentinel 唤醒系统')
       }
       act(() => { root.unmount() })
       container.remove()

tests/plugin-list.spec.ts

@@ -24,9 +24,10 @@ const catalogs: Array<[string, readonly PluginEntry[]]> = [
 ]
 
 describe('builtin plugin catalogs', () => {
-  it('the viewer catalog has the seeded office plugin, the tab catalog does not', () => {
+  it('the viewer catalog has the office plugin, the tab catalog has the sentinel plugin', () => {
     const ids = (list: readonly PluginEntry[]): string[] => list.map(p => p.id)
     expect(ids(builtinViewerPlugins)).toContain('@huanlin/dsh-plugin-better-sidebar-plugin-office')
+    expect(ids(builtinTabPlugins)).toContain('@dsh-external/dsh-sentinel')
     expect(ids(builtinTabPlugins)).not.toContain('@huanlin/dsh-plugin-better-sidebar-plugin-office')
   })