fix(storybook): use named installPrimeVue import in preview.ts

Storybook failed to boot ("module does not provide an export named
'default'"): .storybook/preview.ts did a default import while the
PrimeVue installer is a named-only export (deliberate — f218ac6e
switched to named to stop Vuexy registerPlugins() double-registration).
That commit missed updating preview.ts, so Storybook has been broken on
main since. Align the consumer with the producer (named import, same as
main.ts) rather than re-adding a default export. Pre-existing bug,
unrelated to the GUI-redesign merge.

Co-Authored-By: Claude Opus 4.7 <noreply@anthropic.com>

apps/app/.storybook/preview.ts

@@ -1,7 +1,7 @@
 import type { Preview } from '@storybook/vue3-vite'
 import { setup } from '@storybook/vue3-vite'
 
-import installPrimeVue from '../src/plugins/primevue'
+import { installPrimeVue } from '../src/plugins/primevue'
 
 import '../src/assets/styles/tailwind.css'