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/composables/useOnboarding.ts

@@ -24,7 +24,18 @@ export async function isOnboardingComplete(): Promise<boolean> {
   // as already-onboarded and skip the wizard entirely). Only fall
   // back to localStorage if the backend is unreachable.
   const result = await callWithRetry(() => rpcClient.isOnboardingComplete(), 2)
-  if (result !== null) return result
+  if (result !== null) {
+    // Re-seed the localStorage cache so non-async consumers
+    // (OnboardingWrapper's useVideoBackground computed, etc.) see the
+    // right answer after the user clears site data on an already-
+    // onboarded node.
+    if (result) {
+      try { localStorage.setItem('neode_onboarding_complete', '1') } catch {}
+    } else {
+      try { localStorage.removeItem('neode_onboarding_complete') } catch {}
+    }
+    return result
+  }
   return localStorage.getItem('neode_onboarding_complete') === '1'
 }