fix(ui): first-login dashboard entrance restored + working Replay Intro

- playDashboardLoadOomph gated itself silent on the one entry that
  should be loud: onboarding is already flagged complete by the time the
  post-wizard dashboard mounts. force flag restores the full oomph there
  while keeping ordinary re-logins quiet (the intentional limit).
- OnboardingDone now hands Login a one-shot finale flag, so the login
  right after the wizard gets the full zoom + oomph even as a regular
  password login — which is exactly the demo flow (and TOTP logins).
- 'Replay intro' on the login screen actually replays: App.vue was
  instantly re-marking the intro as seen on onboarded nodes; an explicit
  one-shot replay flag now overrides every suppression rule (unit
  tested).

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

neode-ui/src/App.vue

@@ -395,6 +395,11 @@ onMounted(async () => {
   let seenIntro = localStorage.getItem('neode_intro_seen') === '1'
   const fromBoot = sessionStorage.getItem('archipelago_from_boot') === '1'
   if (fromBoot) sessionStorage.removeItem('archipelago_from_boot')
+  // One-shot "Replay intro" request from the login screen — must survive the
+  // auto-re-mark below (which otherwise instantly suppresses the replay on any
+  // onboarded node).
+  const replayRequested = sessionStorage.getItem('archipelago_replay_intro') === '1'
+  if (replayRequested) sessionStorage.removeItem('archipelago_replay_intro')
   let onboardingComplete: boolean | null = localStorage.getItem('neode_onboarding_complete') === '1' ? true : null
   const splashCandidate = !seenIntro
     && (fromBoot || (route.path === '/' && import.meta.env.VITE_DEV_MODE !== 'boot'))
@@ -408,7 +413,7 @@ onMounted(async () => {
     }
   }
 
-  if (!seenIntro && onboardingComplete === true) {
+  if (!replayRequested && !seenIntro && onboardingComplete === true) {
     try { localStorage.setItem('neode_intro_seen', '1') } catch { /* noop */ }
     seenIntro = true
   }
@@ -421,6 +426,7 @@ onMounted(async () => {
     fromBoot,
     devMode: import.meta.env.VITE_DEV_MODE,
     onboardingComplete,
+    replayRequested,
   })) {
     // Coming from boot screen — show the full splash intro (Enter to Exit → typing → logo)
     showSplash.value = true