Add test-runner configuration to define __test global variable

Co-authored-by: hotlong <50353452+hotlong@users.noreply.github.com>

Author: Copilot

.storybook/test-runner.ts

@@ -0,0 +1,14 @@
+import type { TestRunnerConfig } from '@storybook/test-runner';
+
+const config: TestRunnerConfig = {
+  // Hook that is executed before the test runner starts running tests
+  async preVisit(page) {
+    // Set up any global variables or configurations needed for tests
+    await page.evaluate(() => {
+      // Define __test global if it's being referenced by test infrastructure
+      (window as any).__test = true;
+    });
+  },
+};
+
+export default config;