fix: "Show in folder" reveals in the explorer instead of opening a directory in the editor

The open-path interception reroutes EVERY chat-side file open into the
sidebar editor, including the stock "Show in folder" gesture: the
ui-deliverables row passes "." (resolved to "<cwd>/." by the chat view),
so clicking it opened a bogus editor tab for the workspace directory
(host error: '"..." is a directory').

- openpath-intercept: detect the folder-reveal gesture ("." / "./" /
  "<cwd>/.") and route it to a new revealInExplorer dep instead of the editor.
- intercept: revealInExplorer switches to the explorer tab (expanding the
  panel), expands the produced files' parent directories, and highlights /
  scrolls to them; the intercepted produced-files row now also renders its
  own "Show in folder" button when files are hidden.
- produced-files: selectProducedFiles reads the engine Turn data
  (owner.turn.data.get("deliverables")) — the same source ui-deliverables
  uses — with the node replica as fallback. The old code read owner.nodes,
  which the real TurnTailOwnerProps ({turn, seq, openFile}) does not carry,
  so the takeover never claimed the chain.
- state: transient `revealed` set (never persisted) plus a revealPaths
  reducer that expands ancestor directories.
- ExplorerView: highlight + scroll revealed rows; Sidebar/tabs/service
  thread `revealed` through TabComponentProps.
- tests: folder-gesture routing, engine-data selector, wiring seat, zh/en copy.

src/client/openpath-intercept.ts

@@ -30,13 +30,29 @@ export interface OpenPathInterceptDeps {
   currentSessionId(): string | undefined
   /** Route the open into the sidebar editor (the established openSidebarFile). */
   openInSidebar(path: string, sessionId: string): void
+  /** Route a folder-reveal gesture ("Show in folder" passes '.') into the sidebar explorer. */
+  revealInExplorer(path: string, sessionId: string): void
+}
+
+/**
+ * Whether a path is the "Show in folder" folder-reveal gesture. The stock
+ * ui-deliverables row passes `'.'` (the session workspace root, resolved by
+ * the chat view to `"<cwd>/."`); any path whose final segment is `.` is the
+ * same gesture. A directory has no editor content, so these opens must reach
+ * the explorer instead of an editor tab.
+ */
+export function isFolderRevealPath(path: string): boolean {
+  if (path === '.' || path === './') return true
+  const trimmed = path.replace(/[\\/]+$/, '')
+  return trimmed === '.' || /[\\/]\.$/.test(trimmed)
 }
 
 /**
  * Wrap `workspaces.openPath`: intercepted calls open the file in the sidebar
  * editor instead of the Host OS and resolve as success (the original's
  * callers ignore the result); anything that declines falls through to the
- * original method untouched.
+ * original method untouched. The one exception is the folder-reveal gesture,
+ * which is routed to {@link OpenPathInterceptDeps.revealInExplorer} instead.
  * @param workspaces - the client workspaces service to wrap.
  * @param deps - per-call takeover decisions.
  * @returns the disposer restoring the original method (HMR-safe).
@@ -50,7 +66,8 @@ export function wrapOpenPath(workspaces: OpenPathService, deps: OpenPathIntercep
     if (deps.takeoverEnabled()) {
       const sessionId = deps.currentSessionId()
       if (sessionId !== undefined) {
-        deps.openInSidebar(path, sessionId)
+        if (isFolderRevealPath(path)) deps.revealInExplorer(path, sessionId)
+        else deps.openInSidebar(path, sessionId)
         return Promise.resolve()
       }
     }