fix(hub): assert DB wipe and single-worker integration tests

Fail fast if TRUNCATE left Organization rows, drop the extra deleteMany
before seed create, and force vitest maxWorkers=1 so forks cannot race
the shared Postgres.

hub/test/integration/helpers.ts

@@ -69,16 +69,18 @@ export async function resetDb(): Promise<void> {
       END IF;
     END $$;
   `);
+  const leftover = await prisma.organization.count();
+  if (leftover !== 0) {
+    throw new Error(`resetDb truncate left ${leftover} organization row(s)`);
+  }
   await seedTestOrganization();
 }
+
 export async function seedTestOrganization(
   id: string = DEFAULT_ORG_ID,
   slug: string = "test-default",
 ): Promise<void> {
-  // Prefer explicit create-after-wipe over upsert: leftover half-states after
-  // interrupted tests made Prisma upsert hit unique(id) while where saw zero.
   await prisma.$transaction(async (tx) => {
-    await tx.organization.deleteMany({ where: { OR: [{ id }, { slug }] } });
     await tx.organization.create({
       data: {
         id,

hub/vitest.config.ts

@@ -7,6 +7,7 @@ export default defineConfig({
     // concurrent truncate/insert races. Unit tests are fast either way.
     pool: "forks",
     fileParallelism: false,
+    maxWorkers: 1,
     env: { NODE_ENV: "test" },
   },
 });