add NetBird and CKAN metadata to metrics

[saleemalharir1]

Summary

• add optional NetBird metadata to the metrics payload from NETBIRD_ENABLED, NETBIRD_IP, and NETBIRD_GROUP
• report local CKAN URL and whether a CKAN API key is configured
• report a short CKAN API key fingerprint by default, and the raw key only when REPORT_CKAN_API_KEY_IN_METRICS=True is explicitly set

Notes

This PR is stacked after #197. Review and merge #197 first; after that lands, this PR should collapse to only the metrics changes.

Testing

• python3 -m py_compile api/tasks/metrics_task.py tests/test_metrics_task.py
• git diff --check
• docker compose up --build -d api
• docker compose exec -T api pytest -q tests/test_metrics_task.py