fix(ui): play the intro on backend-confirmed fresh nodes despite stale browser flags

neode_intro_seen / neode_onboarding_complete are per-origin browser state:
after a reinstall (or another node on a DHCP-recycled IP) they describe the
previous node and muted a genuinely fresh install's intro. Root boots now
always ask the backend; a confirmed-fresh answer plays the intro and clears
the stale flag.

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

neode-ui/src/utils/introSplash.ts

@@ -10,10 +10,19 @@ export interface IntroSplashDecisionInput {
 
 export function shouldShowIntroSplash(input: IntroSplashDecisionInput): boolean {
   if (input.replayRequested) return true
+
+  const isDirectRoute = input.routePath !== '/'
+  // A node the backend CONFIRMS has never completed onboarding always gets
+  // the full intro on a root boot. `seenIntro` is per-origin browser state —
+  // after a reinstall (or a DHCP-recycled IP), the browser still carries the
+  // previous node's flag at the same origin, which silently muted the intro
+  // on genuinely fresh installs.
+  if (input.onboardingComplete === false && (input.fromBoot || (!isDirectRoute && input.devMode !== 'boot'))) {
+    return true
+  }
   if (input.seenIntro) return false
   if (input.onboardingComplete === true) return false
 
-  const isDirectRoute = input.routePath !== '/'
   if (input.fromBoot) return true
   if (input.devMode === 'boot') return false
   return !isDirectRoute