chore: use nginx module from charmlibs instead of coordinated-workers

[Copilot]

Issue

The nginx module was extracted from coordinated-workers into the standalone charmlibs.nginx_k8s PyPI package. This charm was still importing nginx utilities directly from coordinated_workers.nginx, which no longer exists in v4.0.0.

Solution

Bump coordinated-workers to >=4.0.0 in both coordinator and worker, and migrate all nginx-related imports to charmlibs.nginx_k8s.

Import migration:

• coordinator/src/charm.py: from charmlibs.nginx_k8s import NginxConfig, TLSConfigManager — cert path constants now derived as TLSConfigManager.{CA_CERT,CERT,KEY}_PATH
• coordinator/src/nginx_config.py: from charmlibs.nginx_k8s import NginxLocationConfig, NginxUpstream — ignore_worker_role renamed to ignore_address_lookup_key

API removals in v4.0.0:

• ClusterRolesConfig no longer accepts recommended_deployment — removed from pyroscope_config.py along with the now-dead RECOMMENDED_DEPLOYMENT constant
• Coordinator._default_degraded_message removed — cleaned up from PyroscopeCoordinator

Test updates:

• Add Exec(["nginx", "-s", "reload"]) to nginx container fixtures (coordinator unit + interface)
• Remove test_recommended from test_coherence.py (Coordinator.is_recommended no longer exists)
• Update test_happy_status_message — expected message changes from "[degraded] UI ready at ..." to "UI ready at ..." (degraded status concept removed upstream)
• Patch Worker._is_readiness_check_failing in worker endpoint_ready fixture

Context

coordinated-workers 4.0.0 extracted the nginx configuration layer into charmlibs-nginx-k8s (a standalone PyPI package). The recommended_deployment concept and associated is_recommended property were also dropped from Coordinator/ClusterRolesConfig in this release. This follows the same migration done for Tempo in tempo-operators#315.

Testing Instructions

cd coordinator && tox -e unit
cd worker && tox -e unit

Upgrade Notes

No user-facing changes. The nginx configuration behaviour is identical; only the library source changed.

[lucabello]

@copilot Can you address conflicts?

[Copilot]

@copilot Can you address conflicts?

Conflicts resolved in 19d1c20. The merge brought in latest main changes:

• coordinator/src/charm.py: removed the module-level CA_CERT_PATH/CERT_PATH/KEY_PATH constants (main already uses TLSConfigManager.* attributes directly throughout the file)
• coordinator/src/nginx_config.py: kept ignore_address_lookup_key=True on the worker upstream
• coordinator/uv.lock, worker/uv.lock: regenerated via uv lock

All unit tests pass (63 coordinator, 23 worker).