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/views/Chat.vue

@@ -217,6 +217,16 @@ function dismissToolConfirm() {
   toolConfirm.value = null
 }
 
+function onToolConfirmExpired(e: Event) {
+  // 13-08 on-device UAT: the node no longer holds this pending action
+  // (timed out, or resolved elsewhere) — close the dialog rather than
+  // leave the human an Approve button whose click can only be refused.
+  const detail = (e as CustomEvent).detail as { reqId?: string }
+  if (toolConfirm.value && detail?.reqId === toolConfirm.value.reqId) {
+    toolConfirm.value = null
+  }
+}
+
 function onAiuiMessage(event: MessageEvent) {
   if (!aiuiUrl.value) return
   // Validate origin — only accept messages from AIUI
@@ -246,6 +256,8 @@ function armChatLive() {
   window.addEventListener('message', onAiuiMessage)
   window.removeEventListener('aiui:tool-confirm-request', onToolConfirmRequest)
   window.addEventListener('aiui:tool-confirm-request', onToolConfirmRequest)
+  window.removeEventListener('aiui:tool-confirm-expired', onToolConfirmExpired)
+  window.addEventListener('aiui:tool-confirm-expired', onToolConfirmExpired)
   broker?.stop()
   broker = null
   if (aiuiUrl.value) {
@@ -266,6 +278,7 @@ onActivated(() => armChatLive())
 onDeactivated(() => {
   window.removeEventListener('message', onAiuiMessage)
   window.removeEventListener('aiui:tool-confirm-request', onToolConfirmRequest)
+  window.removeEventListener('aiui:tool-confirm-expired', onToolConfirmExpired)
   broker?.stop()
   broker = null
   if (loadTimeout) { clearTimeout(loadTimeout); loadTimeout = null }
@@ -280,6 +293,7 @@ onMounted(() => armChatLive())
 onBeforeUnmount(() => {
   window.removeEventListener('message', onAiuiMessage)
   window.removeEventListener('aiui:tool-confirm-request', onToolConfirmRequest)
+  window.removeEventListener('aiui:tool-confirm-expired', onToolConfirmExpired)
   broker?.stop()
   broker = null
   if (loadTimeout) { clearTimeout(loadTimeout); loadTimeout = null }