feat(tailwind): install Tailwind v4 alongside Vuetify (parallel mode)

Three additions wire Tailwind v4 into the SPA without disturbing the
existing Vuetify pipeline:

- apps/app/src/assets/styles/tailwind.css — Tailwind v4 CSS-first entry.
  Uses @import "tailwindcss"; @plugin "tailwindcss-primeui"; and
  @source pointing at apps/app/src/ to scan template content.

- apps/app/vite.config.ts — adds the @tailwindcss/vite plugin between
  vue() and vuetify(). After vue() so it sees compiled template
  content; before vuetify() so Vuetify's SCSS pipeline runs unimpeded.

- apps/app/src/main.ts — imports tailwind.css before the Vuetify/Vuexy
  SCSS so utility classes are available alongside Vuetify's cascade.

optimizeDeps.exclude remains ['vuetify'] (no PrimeVue addition) — HMR
behaves correctly in dev with the current config; revisit if needed.

Verification:
- pnpm typecheck — clean.
- pnpm build — succeeds in 13.97s; CSS emitted per-route as expected.
- pnpm test — 402 tests pass unchanged.

Co-Authored-By: Claude Opus 4.7 (1M context) <noreply@anthropic.com>

apps/app/src/main.ts

@@ -8,6 +8,7 @@ import App from '@/App.vue'
 import { registerPlugins } from '@core/utils/plugins'
 
 // Styles
+import '@styles/tailwind.css'
 import '@core/scss/template/index.scss'
 import '@styles/styles.scss'