chore: update CI configuration and enhance test stability

- Added deterministic API key and environment variables in e2e-tests.yml to ensure consistent test behavior.
- Refactored CodexProvider tests to improve type safety and mock handling, ensuring reliable test execution.
- Updated provider-factory tests to mock installation detection for CodexProvider, enhancing test isolation.
- Adjusted Playwright configuration to conditionally use external backend, improving flexibility in test environments.
- Enhanced kill-test-servers script to handle external server scenarios, ensuring proper cleanup of test processes.

These changes improve the reliability and maintainability of the testing framework, leading to a more stable development experience.

.github/workflows/e2e-tests.yml

@@ -36,6 +36,14 @@ jobs:
         env:
           PORT: 3008
           NODE_ENV: test
+          # Use a deterministic API key so Playwright can log in reliably
+          AUTOMAKER_API_KEY: test-api-key-for-e2e-tests
+          # Reduce log noise in CI
+          AUTOMAKER_HIDE_API_KEY: 'true'
+          # Avoid real API calls during CI
+          AUTOMAKER_MOCK_AGENT: 'true'
+          # Simulate containerized environment to skip sandbox confirmation dialogs
+          IS_CONTAINERIZED: 'true'
 
       - name: Wait for backend server
         run: |
@@ -59,6 +67,8 @@ jobs:
           CI: true
           VITE_SERVER_URL: http://localhost:3008
           VITE_SKIP_SETUP: 'true'
+          # Keep UI-side login/defaults consistent
+          AUTOMAKER_API_KEY: test-api-key-for-e2e-tests
 
       - name: Upload Playwright report
         uses: actions/upload-artifact@v4