feat: AI commit messages, change tree, router behavesAs, sidebar times (v2.2.0)

- Changes panel: Files and Changes merged into one panel; the overview's
  groups drawn as a folder tree (compacted chains, file counts, fold,
  stage/unstage a whole folder)
- AI-suggested commit message for what is staged
  (POST /api/lanes/:id/git/commit-message, claude -p --safe-mode, haiku)
- AI Router: optional "Behaves as" Claude model id, written as
  modelPicker options into the router's --settings file (issue #56)
- Sidebar: session rows show last activity, live rows their start time;
  a closed Terminal row can be removed (DELETE /api/run/history/:id)
- Every pane's CLI starts only once a client is attached; claude panes
  no longer forced inline; tmux scrollbar one column wide
- Update notifier: "Check for updates" reopens a closed notice

client/src/components/__tests__/UpdateNotifier.test.tsx

@@ -238,6 +238,16 @@ describe("UpdateNotifier — closing vs skipping", () => {
     expect(localStorage.getItem("agent-monitor-update-dismissed-sha")).toBe("bbb");
   });
 
+  it("Check for updates re-opens a modal closed with Later", async () => {
+    render(<UpdateNotifier />);
+    await userEvent.click(await screen.findByText(i18n.t("updates:later")));
+    await waitFor(() =>
+      expect(screen.queryByText(i18n.t("updates:title"))).not.toBeInTheDocument()
+    );
+    window.dispatchEvent(new Event("dashboard:reset-update-dismissal"));
+    expect(await screen.findByText(i18n.t("updates:title"))).toBeInTheDocument();
+  });
+
   it("ignores Escape while an update is applying", async () => {
     applyMock.mockReturnValue(new Promise(() => {}));
     render(<UpdateNotifier />);