fix(intro): splash always honors App's decision + video streams 3x lighter

- SplashScreen no longer re-checks neode_intro_seen itself: it silently
  skipped the whole logo-tap/typing sequence for any browser that had
  seen the intro before, even when App.vue explicitly requested it (demo
  fresh visits, Replay Intro). App.vue is the single decision point.
- Intro video re-encoded 12.7MB/12.6Mbps → 4.3MB/4.2Mbps (1920x1080 CRF23
  faststart, muted track dropped) — visually identical on this
  illustrated content; cache-buster bumped to v=8.
- Video is <link rel=preload>ed the moment the splash is scheduled (the
  <video> element only mounts ~20s in, so cold caches used to start the
  download mid-sequence and stutter).
- nginx demo cache regex now covers mp4/webm/mp3/webp/woff2 so repeat
  visits play from browser cache.

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

neode-ui/src/App.vue

@@ -433,6 +433,17 @@ onMounted(async () => {
     onboardingComplete,
     replayRequested,
   })) {
+    // Kick off the intro video download NOW: the splash's <video> element only
+    // mounts ~20s in (after the typing sequence), and on a cold cache the file
+    // would otherwise start fetching mid-sequence and stutter.
+    try {
+      const link = document.createElement('link')
+      link.rel = 'preload'
+      link.as = 'video'
+      link.type = 'video/mp4'
+      link.href = '/assets/video/video-intro.mp4?v=8'
+      document.head.appendChild(link)
+    } catch { /* ignore */ }
     // Coming from boot screen — show the full splash intro (Enter to Exit → typing → logo)
     showSplash.value = true
   } else {