test: run Vitest browser projects headlessly (#2284)

packages/audio-pipelines-transcribe/vitest.config.ts

@@ -25,6 +25,7 @@ export default defineConfig(({ mode }) => ({
           browser: {
             provider: playwright(),
             enabled: true,
+            headless: true,
             // Vitest browser mode requires an explicit browser instance list.
             instances: [
               { browser: 'chromium' },

packages/stage-ui-mmd/vitest.config.ts

@@ -17,6 +17,7 @@ export default defineConfig({
           include: ['src/**/*.browser.test.ts'],
           browser: {
             enabled: true,
+            headless: true,
             provider: playwright(),
             instances: [
               { browser: 'chromium' },

packages/stage-ui/vitest.config.ts

@@ -40,6 +40,7 @@ export default defineConfig(({ mode }) => {
             exclude: ['**/node_modules/**'],
             browser: {
               enabled: true,
+              headless: true,
               provider: playwright(),
               instances: [
                 { browser: 'chromium' },