feat(k8s): replace Kubernetes adapter mock with real cluster discovery

[marcuspat]

v1.1.0 target

The current KubernetesAdapter returns fixture data. Replace with real cluster discovery using the Kubernetes API client.

Scope:

• Wire @kubernetes/client-node against a real cluster
• • Implement namespace/pod/deployment discovery
• • • Update integration tests to use a real or kind cluster
• • • • Remove fixtures from __mocks__/kubernetes*
        Acceptance criteria:
• jest --testPathPattern=kubernetes passes against a live or kind cluster
• • Discovery endpoint returns real cluster topology
• • • Adapter mock flag removed from CI skip list
      Context: v1.0.0 shipped with adapter-mock by design (ADR documents this). This is the first real integration target for v1.1.0.