[FEATURE] [LFX] Headlamp plugin for node-readiness-controller

Is your feature request related to a problem or existing issue? Please describe.

NRC state today is only visible via kubectl, logs, and the Prometheus metrics surface. It may be desirable for the Headlamp users to get answers to "why is this node not accepting workloads?" directly from the UX.

This issue tracks building a plugin for Headlamp to visualize NRC state directly, proposed as a CNCF LFX mentorship project (2026 Term 3). This is a follow-up deliverable from the Term 2 observability project.

Describe the solution you'd like

High-level scope:

• Cluster-level view of NodeReadinessRule objects with live status (nodes matched / held / released per rule, derived from node taints).
• Node-level drill-down: applicable rules, per-condition pass/fail with failure reasons, NRC-managed taints, and related Events.
• Watch-based, API-state only: This doesnt replace the metrics / Grafana. Headlamp will give visibility into per-object questions and capture relationships on the map.
• Align with other standardized node conditions to explore as a generic lifecycle-conditions panel for Node Availability.
• Design doc reviewed by NRC and Headlamp maintainers before implementation.
• Validate and document the UX and scale tests / limits for the plugin.
• Published to Headlamp Artifact Hub with docs.

Describe alternatives you've considered

No response