feat: add pytest-xdist parallel test support with dynamic port allocation

Add pytest-xdist dependency and configure parallel test execution with `-n auto` flag. Implement dynamic port assignment in conftest.py using `_xdist_port()` function that derives unique ports from worker IDs (base 10501 + worker index). Update app server subprocess to use per-worker port and create isolated test databases with port-specific suffixes. Modify test_landing.py to gracefully skip news section test when news service is unavailable by catching timeout exceptions with pytest.skip.

.gitea/workflows/test.yaml

@@ -19,12 +19,12 @@ jobs:
       - name: Install dependencies
         run: |
           pip install -e .
-          pip install playwright
+          pip install playwright pytest-xdist
           python -m playwright install chromium --with-deps
 
       - name: Run integration tests
         run: |
-          python -m pytest tests/ -v --tb=line -x
+          python -m pytest tests/ -n auto -v --tb=line -x
 
       - name: Upload test screenshots
         if: failure()