Extract the duplicated _resolve_service_record helper (identical in
routers/monitoring.py and routers/authentik_users.py) into a shared
services/service_resolution.py module. Both routers now import
resolve_service_record from the shared module.
The authentik router previously hardcoded service_type='authentik' in
its local copy; the shared helper takes service_type as a param (same
as monitoring's did).
Tests updated: test_api.py patches now target the correct module paths
(resolve_service_record on the monitoring module where it's imported,
build_service_record on the service_resolution module).
283 backend tests pass; ruff clean.
Developer