ci: raise Playwright worker count on CI from 1 to 4

workers was hardcoded to 1 on CI, serializing all 150 test instances
(30 tests x 5 browser projects) despite fullyParallel: true, turning a
~2 min suite into 25+ min and causing PR test runs to approach the
job timeout.

Co-Authored-By: Claude Sonnet 5 <noreply@anthropic.com>

Author: IObert

playwright.config.ts

@@ -21,8 +21,7 @@ export default defineConfig({
   forbidOnly: !!process.env.CI,
   /* Retry on CI only */
   retries: process.env.CI ? 2 : 0,
-  /* Opt out of parallel tests on CI. */
-  workers: process.env.CI ? 1 : undefined,
+  workers: process.env.CI ? 4 : undefined,
   /* Reporter to use. See https://playwright.dev/docs/test-reporters */
   reporter: "html",
   /* Shared settings for all the projects below. See https://playwright.dev/docs/api/class-testoptions. */