fix(ui): companion QR absolute 146 URL + Dashboard swipe type guard

- Companion app QR encoded a relative path (/packages/...apk.zip) which
  can't resolve when scanned by a phone. Point it at the absolute 146
  release-server URL so the download works from any device.
- Dashboard tab-swipe: guard tabs[next] (noUncheckedIndexedAccess) so the
  frontend type-checks/builds.

Co-Authored-By: Claude Opus 4.8 (1M context) <noreply@anthropic.com>

neode-ui/src/views/Dashboard.vue

@@ -318,7 +318,9 @@ function onContentTouchEnd(e: TouchEvent) {
   if (idx < 0) return
   const next = idx + (dx < 0 ? 1 : -1) // swipe left → next tab, right → previous
   if (next < 0 || next >= tabs.length) return
-  router.push(tabs[next].to).catch(() => {})
+  const target = tabs[next]
+  if (!target) return
+  router.push(target.to).catch(() => {})
 }
 
 watch(() => route.path, (newPath) => {