feat: add live-test container for the directory adapter

A test stage in the Dockerfile and an opt-in compose profile run the live
directory checks against the test OU inside the image, reading the LDAP_*
values from .env.

Co-Authored-By: Claude Sonnet 5.5 <noreply@anthropic.com>
Claude-Session: https://claude.ai/code/session_01N3t4WL7bd9bdHHNjEsxzqC

Dockerfile

@@ -18,6 +18,12 @@ RUN SECRET_KEY=build-time-only-value-not-used-at-runtime-000000 \
     LDAP_CA_FILE=/app/README.md LDAP_PUBLISHER_GROUP_DN=build LDAP_ADMIN_GROUP_DN=build \
     /app/.venv/bin/python manage.py collectstatic --noinput
 
+# Not part of the runtime image: `docker compose --profile test run --rm live-test`
+FROM builder AS test
+RUN uv sync --frozen --no-install-project
+ENV PATH="/app/.venv/bin:$PATH"
+CMD ["python", "-m", "pytest", "portal/tests/test_directory_live.py", "-v", "-p", "no:cacheprovider"]
+
 FROM python:3.13-slim
 ENV PYTHONUNBUFFERED=1 PYTHONDONTWRITEBYTECODE=1 PATH="/app/.venv/bin:$PATH"
 RUN apt-get update \