release(v1.7.34-alpha): re-seed onboarding cache + rotating login bg + drop re-login zoom

- useOnboarding.ts: when the backend gives a definitive answer
  (true/false, not a null retry failure), re-seed the
  neode_onboarding_complete localStorage flag accordingly. Fixes the
  case where a user clears site data on an already-onboarded node —
  OnboardingWrapper's useVideoBackground computed reads localStorage
  synchronously, so without this re-seed the intro video would fire
  again on /login even though RootRedirect correctly sent them
  straight to /login.
- OnboardingWrapper.vue: login background now rotates through
  bg-intro-1..6 on each /login mount, with the current index
  persisted to localStorage (neode_login_bg_idx) so subsequent
  logouts advance rather than repeat the same image.
- Dashboard.vue: subsequent-login branch drops the 1.2s showZoomIn
  entirely. Only the first dashboard entry after onboarding plays
  the full zoom + glitch reveal; every re-login now just fades in
  with the welcome typing (~300ms).

Co-Authored-By: Claude Opus 4.7 (1M context) <noreply@anthropic.com>

neode-ui/src/views/Dashboard.vue

@@ -285,17 +285,15 @@ onMounted(() => {
       loginTransition.setPendingWelcomeTyping(false)
     }, 4000)
   } else if (loginTransition.justLoggedIn) {
-    // Regular re-login — quick interface draw, no triple glitch flashes.
-    // Just the zoom-in for a short beat, then welcome typing fires fast.
+    // Regular re-login — no zoom, no glitch. Just land on the
+    // dashboard and kick off the welcome typing quickly.
     playDashboardLoadOomph()
-    showZoomIn.value = true
     loginTransition.setPendingWelcomeTyping(true)
     loginTransition.setJustLoggedIn(false)
-    scheduledTimeout(() => { showZoomIn.value = false }, 1200)
     scheduledTimeout(() => {
       loginTransition.setStartWelcomeTyping(true)
       loginTransition.setPendingWelcomeTyping(false)
-    }, 600)
+    }, 300)
   }
 
   window.addEventListener('keydown', handleKioskShortcuts)