feat: improve test setup and authentication handling

- Added `dev:test` script to package.json for streamlined testing without file watching.
- Introduced `kill-test-servers` script to ensure no existing servers are running on test ports before executing tests.
- Enhanced Playwright configuration to use mock agent for tests, ensuring consistent API responses and disabling rate limiting.
- Updated various test files to include authentication steps and handle login screens, improving reliability and reducing flakiness in tests.
- Added `global-setup` for e2e tests to ensure proper initialization before test execution.

apps/ui/tests/agent/start-new-chat-session.spec.ts

@@ -16,6 +16,7 @@ import {
   clickNewSessionButton,
   waitForNewSession,
   countSessionItems,
+  authenticateForTests,
 } from '../utils';
 
 const TEST_TEMP_DIR = createTempDirPath('agent-session-test');
@@ -61,6 +62,7 @@ test.describe('Agent Chat Session', () => {
   test('should start a new agent chat session', async ({ page }) => {
     await setupRealProject(page, projectPath, projectName, { setAsCurrent: true });
 
+    await authenticateForTests(page);
     await page.goto('/');
     await waitForNetworkIdle(page);