Switch PWA service worker to autoUpdate to avoid stale bundles after deploy

VitePWA's registerType: 'prompt' kept the new service worker waiting
indefinitely because no update-prompt UX was wired. Returning visitors
kept receiving the old precached app shell and hashed chunks. 'autoUpdate'
uses skipWaiting + clientsClaim so a deploy takes over on the next
navigation.

Refs: #86

ui/vite.config.ts

@@ -173,7 +173,7 @@ const config = defineConfig({
     tanstackStart({ spa: { enabled: true } }),
     VitePWA({
       injectRegister: false,
-      registerType: "prompt",
+      registerType: "autoUpdate",
       outDir: ".output/public",
       devOptions: {
         enabled: true,