Fix Buildkite CI

Overview

Diagnose Buildkite failures programmatically and avoid guessing from UI screenshots. Prefer structured build/job JSON plus artifact inspection to find the exact failing test case and mismatch, then implement the smallest correct fix.

Target Selection

Resolve triage target with this precedence:

• If user provides a Buildkite build URL, use that build directly.
• Else if user specifies a branch and/or a pipeline (for example pull-request, main-cron), use the specified scope.
• Else default to the current git branch and inspect the checks for the PR associated with that branch.

Workflow