fix(ui): companion popup waits for sustained calm; connection banner stops crying wolf

Two "unpolished" moments, worst on the demo:

- CompanionIntroOverlay gated on a point-in-time check of the reveal
  cinematic flag. On a cold cache the entrance video can start buffering
  after the 5s base delay, so the flag was still false when sampled and
  the popup cut into the cinematic anyway. It now shows only after the
  scene has been continuously calm for the full grace window.

- ConnectionBanner's flat 2.5s debounce fired on every tab-return and on
  first dashboard paint: a dead WebSocket is the NORMAL state right then
  (browsers kill background-tab sockets; first paint races the initial
  connect), and reconnects routinely exceed 2.5s over real links. Those
  moments now get a 10s runway (15s window after load/resume); genuine
  mid-session drops keep the 2.5s response. On the demo the blip banner
  is suppressed entirely — it runs against a local mock, so "Connection
  lost" there is pure noise.

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

neode-ui/src/components/CompanionIntroOverlay.vue

@@ -75,7 +75,7 @@
 </template>
 
 <script setup lang="ts">
-import { ref, onMounted, watch } from 'vue'
+import { ref, onMounted, onUnmounted, watch } from 'vue'
 import * as QRCode from 'qrcode'
 import { IS_DEMO } from '@/composables/useDemoIntro'
 import { useLoginTransitionStore } from '@/stores/loginTransition'
@@ -101,6 +101,8 @@ const loginTransition = useLoginTransitionStore()
 const BASE_DELAY_MS = 5000
 const POST_INTRO_GRACE_MS = 2000
 
+let calmTicker: ReturnType<typeof setInterval> | null = null
+
 onMounted(() => {
   try {
     if (localStorage.getItem(STORAGE_KEY) !== '1') {
@@ -111,21 +113,29 @@ onMounted(() => {
   }
 })
 
+onUnmounted(() => {
+  if (calmTicker) clearInterval(calmTicker)
+})
+
 function maybeShow() {
-  if (loginTransition.introCinematicPlaying) {
-    // First-visit reveal is still running — hold until it finishes.
-    const stop = watch(
-      () => loginTransition.introCinematicPlaying,
-      (playing) => {
-        if (!playing) {
-          stop()
-          setTimeout(() => { visible.value = true }, POST_INTRO_GRACE_MS)
-        }
-      },
-    )
-    return
-  }
-  visible.value = true
+  // Show only after the scene has been CONTINUOUSLY calm (no reveal
+  // cinematic) for the full grace window. The previous point-in-time check
+  // raced a slow-starting reveal — on a cold cache the entrance video can
+  // begin buffering after the 5s base delay, so the flag was still false
+  // when sampled and the popup cut straight into the cinematic.
+  let calmSince = loginTransition.introCinematicPlaying ? null : Date.now()
+  calmTicker = setInterval(() => {
+    if (loginTransition.introCinematicPlaying) {
+      calmSince = null
+      return
+    }
+    if (calmSince === null) calmSince = Date.now()
+    if (Date.now() - calmSince >= POST_INTRO_GRACE_MS) {
+      if (calmTicker) clearInterval(calmTicker)
+      calmTicker = null
+      visible.value = true
+    }
+  }, 250)
 }
 
 watch(visible, async (isVisible) => {