perf: speed up e2e tests in CI

- Pre-build before Playwright instead of building inside webServer
- Reduce retries from 2 to 1 (fix flaky tests instead of masking them)
- Set CI workers to 4 for more parallelism
- Reduce artifact retention from 30 to 7 days

Co-Authored-By: Claude Opus 4.6 <noreply@anthropic.com>

playwright.config.ts

@@ -4,7 +4,8 @@ export default defineConfig({
 	testDir: './tests/e2e',
 	fullyParallel: true,
 	forbidOnly: !!process.env.CI,
-	retries: process.env.CI ? 2 : 0,
+	retries: process.env.CI ? 1 : 0,
+	workers: process.env.CI ? 4 : undefined,
 	reporter: 'html',
 	globalSetup: './tests/e2e/global-setup.ts',
 	use: {
@@ -27,7 +28,7 @@ export default defineConfig({
 		}
 	],
 	webServer: {
-		command: 'pnpm build && pnpm preview --port 4173',
+		command: 'pnpm preview --port 4173',
 		port: 4173,
 		reuseExistingServer: !process.env.CI,
 		timeout: 120_000,