perf(test): auto-unstub globals

vitest.config.ts

@@ -21,6 +21,8 @@ export default defineConfig({
     // Many suites rely on `vi.stubEnv(...)` and expect it to be scoped to the test.
     // This is especially important under `pool=vmForks` where env leaks cross-file.
     unstubEnvs: true,
+    // Same rationale as unstubEnvs: avoid cross-test pollution under vmForks.
+    unstubGlobals: true,
     pool: "forks",
     maxWorkers: isCI ? ciWorkers : localWorkers,
     include: ["src/**/*.test.ts", "extensions/**/*.test.ts", "test/format-error.test.ts"],