fix(13-08): confirm timeout 120s→300s + chrome closes an expired dialog

On-device UAT: the operator was timed out mid-read (120s), the chat turn
returned 'declined' while the dialog was still up, and their Approve then
hit a dead entry ('no such pending confirmation', 13:37:12 log). Nothing
executed — the gate failed safe — but the UX was a lie in both directions.

- CONFIRM_TIMEOUT 120s→300s: human-speed per T-13-51's own rubric.
- ContextBroker dispatches aiui:tool-confirm-expired when a pending action
  vanishes node-side (poll) or the turn ends; Chat.vue closes the modal on
  it. Same host-only CustomEvent discipline; iframe has no path to it.
- Two new tests; 21/21 green across toolConfirm + chatAiuiEmbed.

Co-Authored-By: Claude Fable 5 <noreply@anthropic.com>

neode-ui/src/services/__tests__/toolConfirm.test.ts

@@ -112,6 +112,56 @@ describe('tool confirmation — ContextBroker half', () => {
     await chat
   })
 
+  it('a confirmation that vanishes node-side is expired to the chrome so the dialog closes', async () => {
+    let currentPending: typeof PENDING_IMMICH | null = PENDING_IMMICH
+    let releaseChat: (v: unknown) => void = () => {}
+    vi.mocked(rpcClient.call).mockImplementation((opts: { method: string }) => {
+      if (opts.method === 'assistant.chat') {
+        return new Promise<unknown>((resolve) => {
+          releaseChat = resolve
+        }) as Promise<never>
+      }
+      if (opts.method === 'assistant.pending') {
+        return Promise.resolve({ pending: currentPending }) as Promise<never>
+      }
+      return Promise.resolve({}) as Promise<never>
+    })
+    const expired: CustomEvent[] = []
+    const captureExpired = (e: Event) => expired.push(e as CustomEvent)
+    window.addEventListener('aiui:tool-confirm-expired', captureExpired)
+
+    const chat = startChat()
+    await vi.advanceTimersByTimeAsync(2000)
+    expect(confirmRequests).toHaveLength(1)
+
+    // The node times the confirmation out: pending goes null mid-turn.
+    currentPending = null
+    await vi.advanceTimersByTimeAsync(2000)
+    expect(expired).toHaveLength(1)
+    expect(expired[0]!.detail.reqId).toBe('confirm-1')
+
+    window.removeEventListener('aiui:tool-confirm-expired', captureExpired)
+    releaseChat({ text: 'done' })
+    await chat
+  })
+
+  it('the chat turn ending expires any confirmation still on screen', async () => {
+    const releaseChat = mockChatSuspendedWithPending(PENDING_IMMICH)
+    const expired: CustomEvent[] = []
+    const captureExpired = (e: Event) => expired.push(e as CustomEvent)
+    window.addEventListener('aiui:tool-confirm-expired', captureExpired)
+
+    const chat = startChat()
+    await vi.advanceTimersByTimeAsync(2000)
+    expect(confirmRequests).toHaveLength(1)
+
+    releaseChat()
+    await chat
+    expect(expired).toHaveLength(1)
+    expect(expired[0]!.detail.reqId).toBe('confirm-1')
+    window.removeEventListener('aiui:tool-confirm-expired', captureExpired)
+  })
+
   it('approving calls assistant.confirm-tool over the page RPC session carrying the node-minted nonce', async () => {
     const releaseChat = mockChatSuspendedWithPending(PENDING_IMMICH)
     const chat = startChat()