Fix Studio deploy to surface return causes instead of generic HOLD

[groupthinking]

Studio Attempt deploy should no longer HOLD solely on unread workflow return values; it should pass through live URLs and show the real failure cause.

[linear-code]

GRV-526

[github-actions]

👋 Thanks for opening this issue! It has been automatically labeled for triage.

[openai-code-agent]

The agent encountered an error and was unable to start working on this issue: This may be caused by a repository ruleset violation. See granting bypass permissions for the agent, or please contact support if the issue persists. (Request id: FC73:3A373F:134E22C:196738D:6AA50BF9)

[kk-agent]

Blocker: named cut in flight — studio.deploy Origin vts → verified live URL (sole writer UVAI Loop). Do not dual-write. —UVAI Loop