perf: speed up local test runs by moving coverage to optional script

Run vitest without coverage by default (pnpm test) and add pnpm test:coverage which enforces the coverage thresholds. CI keeps using the coverage run so thresholds are still enforced on every push.

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

@@ -25,7 +25,7 @@ describe("CI workflow", () => {
 	it("check runs lint, typecheck, and test", () => {
 		expect(workflow).toContain("pnpm biome:lint");
 		expect(workflow).toContain("pnpm typecheck");
-		expect(workflow).toContain("pnpm test");
+		expect(workflow).toContain("pnpm test:coverage");
 	});
 
 	it("check job runs on self-hosted runner", () => {