Ci speed a improvements

[davidpcls]

Summary

it's been long enough I don't know if this is still useful or not. I think perhaps we need to break this down differently.

• Reduce test runtime by reusing a module-scoped RE Manager in auth-focused suites (test_access_control.py, test_auth_api.py) where manager state is not intentionally mutated.
• Enable parallel pytest execution in CI with pytest-xdist and --dist=loadfile.
• Make test infrastructure xdist-safe by isolating worker resources:
  • dynamic per-worker HTTP server port
  • dynamic per-worker ZMQ control/info ports
  • worker-specific xprocess process name

Why

• Auth test suites were paying repeated RE Manager startup/teardown costs per test, adding avoidable overhead.
• Parallel execution previously risked cross-worker collisions on fixed ports and shared process names.
• This change keeps behavior stable while unlocking meaningful CI speedups.

Implementation Details

• Added re_manager_module fixture in bluesky_httpserver/tests/conftest.py and switched auth suites to use it.
• Added queue clear in test_resource_access_01 to preserve deterministic behavior with shared manager lifetime.
• Added worker-aware helpers in bluesky_httpserver/tests/conftest.py to assign unique ports and env vars per xdist worker.
• Overrode re_manager fixture in local conftest.py to start ReManager on worker-specific ZMQ ports.
• Updated xprocess server naming to include worker id to avoid worker lock/name collisions.
• Added pytest-xdist to requirements-dev.txt.
• Updated CI pytest options to: --durations=20 -n auto --dist=loadfile.

Validation

• uv run pre-commit run --all-files
• uv run pytest bluesky_httpserver/tests/test_auth_api.py -q
• uv run pytest bluesky_httpserver/tests/test_access_control.py -q
• uv run pytest -q -n 2 --dist=loadfile bluesky_httpserver/tests/test_auth_api.py bluesky_httpserver/tests/test_core_api_main.py -k "test_http_server_start_01 or test_http_server_ping_handler or test_api_auth_post_apikey_01"

Expected Impact

• Lower per-run overhead from auth suites due to shared manager startup.
• Additional CI wall-time reduction from parallelized test execution on GitHub runners.