Attribution series: pod → workload / component / component instance

[lavianalon]

Part of #336.

Emit one series per attributed pod carrying workload, component, and component_instance labels, resolved from the Karta description.

Requirements:

• Covers only workloads with a matching Karta description.
• Ownership chains (e.g. DynamoGraphDeployment → Grove, JobSet → Job): attribute to the topmost described owner only; nested described objects appear as component/instance labels, never as separate workloads, so every pod counts exactly once. A standalone instance of a nested type is its own workload.
• Reflects cluster state within 30s (watch-driven, no polling).
• Names and labels are a versioned public interface; renames are breaking changes.