fix(intro): audible entrance oomph, splash off deep routes, finale on intro shortcuts — with e2e cinematic suite

Three first-visit-experience bugs, all caught by the new e2e suite
(e2e/intro-experience.spec.ts — 5 tests against the demo stack on real
Chrome, instrumenting HTMLMediaElement/WebAudio/MutationObserver since
headless can't hear or see the cinematic):

- playDashboardLoadOomph was always silent: the login→dashboard route
  change closes the AudioContext (stopAllAudio), and the oomph only
  fetched the dead context. It now recreates one, riding the login
  click's sticky user activation.
- A direct /login load in the demo hijacked into the splash: App.vue
  read route.path before the router resolved the initial navigation, so
  every deep-route boot looked like a root boot. The splash decision now
  reads window.location.pathname.
- Replayed intros ran mute (enableCinematicSounds override) and the
  intro's shortcut exits skipped the dashboard finale (flag now armed on
  both demo and login exits).

Verified: 5/5 e2e, 673/673 unit, vue-tsc clean.

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

neode-ui/src/composables/useLoginSounds.ts

@@ -8,14 +8,27 @@
  * exempt and continue to play regardless.
  */
 
+/** One-way, per-page-load override: when App.vue decides to run the intro
+ *  splash (demo fresh boot, prod first install, Replay Intro), the WHOLE
+ *  cinematic — speech, synthwave, pops — must be audible even though
+ *  localStorage already says onboarding is complete. Without this the
+ *  replayed intro runs silent (lost "Welcome Noderunner" + song). */
+let cinematicMode = false
+export function enableCinematicSounds() {
+  cinematicMode = true
+}
+
 /** True when the node has not yet completed onboarding — i.e. we're
- *  still in the first-install cinematic. Reads the localStorage cache
- *  set by useOnboarding (which is re-seeded from the backend on each
- *  successful check), so this stays correct after a browser clear
- *  once the onboarding-complete probe runs. Sound calls that fire
- *  before that probe completes will fall through silent on an already-
- *  onboarded node — which is exactly what we want. */
+ *  still in the first-install cinematic — or when the intro is being
+ *  deliberately replayed this page load (see enableCinematicSounds).
+ *  Reads the localStorage cache set by useOnboarding (which is
+ *  re-seeded from the backend on each successful check), so this stays
+ *  correct after a browser clear once the onboarding-complete probe
+ *  runs. Sound calls that fire before that probe completes will fall
+ *  through silent on an already-onboarded node — which is exactly what
+ *  we want: ordinary re-logins stay quiet. */
 function isFirstInstallPhase(): boolean {
+  if (cinematicMode) return true
   try {
     return localStorage.getItem('neode_onboarding_complete') !== '1'
   } catch {
@@ -260,7 +273,10 @@ export function playKeyboardTypingSound() {
  */
 export function playDashboardLoadOomph(force = false) {
   if (!force && !isFirstInstallPhase()) return
-  const ctx = getContext()
+  // The login→dashboard route change runs stopAllAudio(), which CLOSES the
+  // AudioContext — so the context must be recreated here, not just fetched.
+  // The login click's sticky user activation lets the fresh context run.
+  const ctx = ensureContext()
   if (!ctx) return
 
   try {