First-run setup wizard (/setup)

- setup_complete site setting; a fresh admin is steered to /setup until it is
  finished (skippable for the session).
- SetupWizard.vue: Site (facility/base-url/access-domain), Features (plugin
  enable/disable), Floor Map dimensions, Starter Data (seed common vendors),
  Finish. Reuses the settings + plugins APIs.
- setup blueprint: POST /setup/seed-starter (idempotent common vendors) and
  POST /setup/complete. setupState composable drives the router redirect.

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

frontend/src/composables/setupState.js

@@ -0,0 +1,28 @@
+// Tracks whether first-run setup is complete, so the app can steer a fresh
+// admin into the /setup wizard. Defaults to "complete" so the wizard never
+// flashes before the real value loads.
+import { ref } from 'vue'
+import { settingsApi } from '../api'
+
+export const setupComplete = ref(true)
+// Session-only: a fresh admin who clicks "Skip for now" is not nagged again
+// until the next login/reload.
+export const setupSkipped = ref(false)
+const loaded = ref(false)
+
+export function isSetupLoaded() {
+  return loaded.value
+}
+
+export async function refreshSetupState() {
+  try {
+    const response = await settingsApi.get('setup_complete')
+    const value = response.data?.data?.value
+    setupComplete.value = value === true || value === 'true'
+  } catch (err) {
+    // If we cannot read it, assume complete so we do not trap the user.
+    setupComplete.value = true
+  }
+  loaded.value = true
+  return setupComplete.value
+}