Cluster Agent validity in the create workspace form

Problem Statement

Currently, when a user attempts to create a workspace with an invalid or unusable cluster agent, there is no useful or actionable feedback provided. The system simply indicates that the agent cannot be used without explaining why, leaving users without clear guidance on how to resolve the issue.

Proposed Solution

Implement a validation system for cluster agents in the workspace creation form that:

1. Provides clear, actionable error messages that explain why an agent is unusable
2. Offers guidance on how to fix common agent configuration issues

Open Questions

• Should users be able to see the validity status of their selected agent before submitting the form?

Technical Considerations

• This will require backend modifications to expose agent validation data in the UI
• May involve coordination with the ~"group::environments" team as they own the agent-related code
• Will need a new GraphQL endpoint to support the validation functionality
• Should be implemented behind a feature flag initially

Related Issues

• Backend issue: GraphQL: Add endpoint to validate a devfile (#410907 - closed)
• Split from: Frontend: Display devfile validity in create wo... (#408742)