feat: 拦截聊天区文件打开 — 聊天里的文件点击默认开进侧边栏编辑器

包装 ctx.workspaces.openPath（聊天区文件打开的唯一漏斗），接管时
经 openSidebarFile 开进 sidebar 编辑器而非系统默认应用；由
interceptOpenPath pref（默认开）与 editor tab 启用态双重门控，
拒接时原样放行，dispose 还原原始方法引用（HMR 安全）。

- prefs-shared/config/prefs: 新增 interceptOpenPath 字段（默认 true）
- openpath-intercept.ts: 零依赖包装器，纯插件层面实现，不改 DSH
- intercept.tsx: registerOpenPathInterception 接线（当前会话 scope）
- SideCardSection: 常规区新增开关卡片（zh/en 文案）
- 测试: 包装器单测 6 个 + 接线集成测试 + pref 解析/设置页断言更新

src/context-types.ts

@@ -232,6 +232,17 @@ export interface SidebarConversation {
   }
 }
 
+/**
+ * The client workspaces service face (mirror of the runtime IWorkspaces). Only
+ * the chat's file-open funnel is touched: `openPath` hands an absolute path
+ * to the Host OS's default application, and every chat-side file open
+ * (tool rows, produced-files, prose mentions) funnels through it.
+ */
+export interface SidebarWorkspacesService {
+  /** Open a filesystem path with the Host operating system's default application. */
+  openPath(path: string): Promise<void>
+}
+
 /**
  * The invariant service face (mirror of @deepseek-ai/dsh-invariants'
  * InvariantService). The upstream augmentation does not reach this Context
@@ -307,6 +318,7 @@ declare module 'cordis' {
     connection: SidebarConnectionHandle
     loader: SidebarLoader
     slots: SidebarSlotsService
+    workspaces: SidebarWorkspacesService
     settings: SidebarSettingsService
     invariants: SidebarInvariantsService
     tools: SidebarToolsService