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/helpers/database.ts

@@ -0,0 +1,19 @@
+import { prisma } from '../integration/setup';
+
+/**
+ * Truncates every table in the public schema (except _prisma_migrations)
+ * so each test starts from an empty database. Sequences are reset to keep
+ * autoincrement ids predictable.
+ */
+export async function resetDatabase() {
+  const tables = await prisma.$queryRawUnsafe<{ tablename: string }[]>(
+    `SELECT tablename::text AS tablename FROM pg_tables
+     WHERE schemaname = 'public' AND tablename <> '_prisma_migrations'`
+  );
+  if (tables.length === 0) return;
+
+  const list = tables.map(({ tablename }) => `"public"."${tablename}"`);
+  await prisma.$executeRawUnsafe(
+    `TRUNCATE ${list.join(', ')} RESTART IDENTITY CASCADE;`
+  );
+}