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/service.ts

@@ -125,6 +125,8 @@ export interface TabComponentProps {
   visible: boolean
   /** The explorer's expanded directory set (ExplorerView). */
   expanded?: string[]
+  /** The explorer's reveal-highlight set (ExplorerView; "Show in folder" targets). */
+  revealed?: string[]
   onToggleDir?: (path: string) => void
   onReferenceFile?: (path: string) => void
   onOpenFile?: (path: string) => void