[EPIC] - CareInstructions UI for shoot-grafter

[uwe-mayer]

Description

Create a Greenhouse UI application that visualizes CareInstruction resources from the shoot-grafter operator. This UI will provide operators with an at-a-glance view of all CareInstructions in their organization, their health status, which Shoots are being onboarded, and any issues that need attention. The UI should serve as a jump-off point to the Greenhouse Cluster resources created by each CareInstruction, enabling seamless navigation from onboarding status to the managed clusters themselves.

Objectives

• Provide a list/overview view of all CareInstructions within an organization namespace
• Visualize the health and readiness state of each CareInstruction (conditions as status indicators)
• Display shoot onboarding statistics (total/effective/excluded/created/failed counts)
• Show per-shoot status details (Onboarded/Failed/Excluded) with error messages
• Surface CareInstruction spec configuration (garden cluster, namespace, selectors, label propagation) in a readable format
• Enable drill-down from CareInstruction to individual shoot status details
• Provide navigation links from managed shoots to their corresponding Greenhouse Cluster resources

Acceptance Criteria

• CareInstructions list view showing all CareInstructions with summary status (Ready/Not Ready), shoot counts, and age
• CareInstruction detail view showing:
  • Spec configuration (garden cluster reference, namespace, shoot selector, propagated labels, additional labels, RBAC/OIDC config)
  • Status conditions rendered as status badges (Ready, GardenClusterAccessReady, ShootControllerStarted, ShootsReconciled)
  • Shoot statistics (totalTargetShootCount, createdClusters, failedClusters) as visual indicators/counters
  • Shoots table listing all shoots with their status (Onboarded/Failed/Excluded) and messages
  • Jump-off links from onboarded shoots to their corresponding Greenhouse Cluster resource detail views
• UI is registered as a uiApplication in the shoot-grafter PluginDefinition

Additional Notes

• The UI should follow the existing Greenhouse UI micro-frontend pattern (like doop, heureka, supernova) using the Juno UI framework
• The CareInstruction status has a shoots array with per-shoot status — this is the primary data to visualize for operational awareness
• CEL expressions in the shootSelector could be displayed as code blocks for readability
• Error states (failed clusters, CEL filter errors) should be prominently highlighted
• Consider adding filtering/sorting on the shoots table by status (show Failed first)