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.

server/api/health.get.ts

@@ -0,0 +1,5 @@
+import { checkDb } from '../db/client'
+
+export default defineEventHandler(async () => {
+  return { ok: true, db: await checkDb() }
+})