catalog: add dsh-video-preview (video previewer) to the file-previewer recommended plugins (#126)

* catalog: add dsh-video-preview to the file-previewer recommended plugins

Adds the video preview plugin (dsh-video-preview) to the "add preview plugin" modal catalog, with zh/en descriptions. Data integrity is guarded by tests/plugin-list.spec.ts.

* test: make add-plugin-modal window.open count catalog-driven

The test pinned the viewer catalog to a single entry (2 "Open:" buttons).
Adding a second recommended plugin (dsh-video-preview) renders 4 buttons
and broke the hardcoded assertion. Derive the expected count from
builtinViewerPlugins so adding/removing plugins keeps the test honest.

src/client/locales.ts

@@ -228,6 +228,7 @@ export const zh = {
   pluginOfficeDesc: '为 better-sidebar 编辑器提供 Office 三件套预览（.docx / .xlsx / .pptx），把重型 Office 渲染库拆出主包、按需安装',
   pluginSentinelDesc: '条件驱动的 agent 唤醒系统：文件/进程/端口/HTTP/命令/webhook 传感器，条件达成自动唤醒休眠会话；注册「哨兵」Tab 展示服务器全局监控表',
   pluginSidebarQaDesc: '基于 better-sidebar 的划选提问tab分页: 对话划选 → 右侧面板提问 → 同工作区独立追问会话（❓追问·主题）：快速无思考模型压缩主对话上下文后与引文一起注入，不打断主对话；追问可嵌套、可继续、可归档',
+  pluginVideoPreviewDesc: '在 better-sidebar 编辑器内联预览视频文件（.mp4/.webm/.mov/.mkv/.avi 等），自带支持 HTTP Range（206）的 /video 宿主路由，可拖动进度条、不受 20MB mediaLimit 限制',
 }
 
 /** The en dictionary (key-set-equal to zh, enforced by the type annotation). */
@@ -449,6 +450,7 @@ export const en: Record<keyof typeof zh, string> = {
   pluginOfficeDesc: 'Office-suite preview (.docx / .xlsx / .pptx) for the better-sidebar editor, keeping the heavy Office render libraries out of the core bundle',
   pluginSentinelDesc: 'Condition-driven agent wakeup: file/process/port/http/command/webhook sensors wake dormant sessions when conditions fire; registers a "Sentinel" tab with the server-wide watch table',
   pluginSidebarQaDesc: 'Select-and-ask: Select conversation text → ask in the right-side panel → a dedicated follow-up session (❓追问) in the same workspace; a fast no-thinking model compresses the main context and injects it with the quote, without interrupting the main conversation. Follow-ups nest, continue, and archive',
+  pluginVideoPreviewDesc: 'Inline video preview (.mp4/.webm/.mov/.mkv/.avi etc.) for the better-sidebar editor, backed by a dedicated /video host route with HTTP Range (206) support — scrubbing works and files are not capped by the 20MB mediaLimit',
 }
 
 /**

src/client/plugins-viewers.ts

@@ -20,4 +20,11 @@ export const builtinViewerPlugins: readonly PluginEntry[] = [
     description: () => t('pluginOfficeDesc'),
     install: 'cd ~/.dsh && dsh plugin --profile web add @huanlin/dsh-plugin-better-sidebar-plugin-office',
   },
+  {
+    id: 'dsh-video-preview',
+    name: '视频预览插件',
+    url: 'https://github.com/zemul/dsh-video-preview',
+    description: () => t('pluginVideoPreviewDesc'),
+    install: 'cd ~/.dsh && dsh plugin --profile web add dsh-video-preview',
+  },
 ]