proposal: support role: worker workloads

[atkrad]

role: worker was in the schema and init wizard, but deploy still failed with role worker is not supported yet. Queue consumers could not ship as first-class components.

Shipped in #75. Workers are long-running Deployments or StatefulSets. No ClusterIP Service, no Ingress. Reject port, expose, health.ready, and HTTP liveness. Optional health.alive.exec only. CPU/memory HPA stays. shutdownTimeout maps to terminationGracePeriodSeconds (default 60s).

Prometheus: services get a ServiceMonitor; workers get a PodMonitor and must set metrics.port. Platform profile owns monitorLabels. In-place role changes are rejected.

components:
  orders-consumer:
    image: ghcr.io/acme/shop:${TAG}
    role: worker
    command: ["/app/worker"]
    metrics:
      port: 9090

Finite work is tasks: (#17), not role: job. Queue-depth HPA is KEDA (#25).

Related: #16, #17, #25, #35, #79.