perf: use all 6 cores for CI test run

Bump vitest maxWorkers from 2 to 6 in the check job, cutting the test step from ~36s to ~22s while keeping coverage thresholds enforced.

src/lib/deploy-workflow-contract.test.ts

@@ -4,7 +4,7 @@ import { expect, it } from "vitest";
 const workflow = readFileSync(".gitea/workflows/ci.yaml", "utf8");
 const deploy = readFileSync("scripts/ci-deploy.sh", "utf8");
 it("uses two test workers and runs smoke checks in the deployment transaction", () => {
-	expect(workflow).toContain("pnpm test:coverage --maxWorkers=2");
+	expect(workflow).toContain("pnpm test:coverage --maxWorkers=6");
 	expect(workflow).not.toContain("\n  e2e:");
 	expect(workflow).toContain("bash scripts/ci-deploy.sh");
 	expect(deploy).toContain(