test(integration): add real-stack integration test suite with PGlite

- PGlite (in-memory WASM Postgres) hosted in a child process, exposed
  via TCP socket; real migrations applied with prisma migrate deploy
- Vitest harness (vitest.integration.config.ts, global-setup spawns
  PGlite + built Nuxt server, per-test TRUNCATE, factories, cookie-jar
  API client); no mocks, zero production code changes
- 50 tests across auth, hunt, team, submit, review, showcase, diashow
  incl. SuperJSON envelope check; *.itest.ts keeps bun test untouched
- CI: parallel unit + integration jobs in .github/workflows/test.yml
- tests/ covered by nuxt typecheck via tests/tsconfig.json reference

tests/integration/health.itest.ts

@@ -0,0 +1,11 @@
+import { describe, expect, it } from 'vitest';
+import { api } from '../helpers/api';
+
+// Proves the full loop: PGlite -> migrations -> build -> server -> fetch.
+describe('health', () => {
+  it('reports a working database connection', async () => {
+    const res = await api.get('/api/health');
+    expect(res.status).toBe(200);
+    expect(await res.json()).toEqual({ ok: true, db: true });
+  });
+});