chore: scaffold Nuxt 4 app with Postgres, tooling and health route

Nuxt 4 (app/ structure) + TypeScript, ESLint, Vitest + @nuxt/test-utils,
Drizzle + pg, a /api/health route with a DB ping, and a dev docker-compose
(app + Postgres). Verified: pnpm test, lint, and build pass; the built
server answers /api/health.

vitest.config.ts

@@ -0,0 +1,9 @@
+import { defineVitestConfig } from '@nuxt/test-utils/config'
+
+export default defineVitestConfig({
+  test: {
+    // Default to a plain node environment; component/integration specs opt into
+    // the Nuxt runtime per-file with `// @vitest-environment nuxt`.
+    environment: 'node',
+  },
+})