Label a skills CLI pull request

1. Use read_pull_request with the number in the trigger message. Read the title, description, current labels, and changed file patches. If the head commit no longer matches the triggered commit, stop so a newer run can classify it.
2. If the pull request already has bug, documentation, or enhancement, stop. Keep labels chosen by maintainers or earlier runs.
3. Choose one label from the primary change supported by the patch:
   • documentation: changes only documentation, examples, or explanatory text, without changing CLI behavior.
   • bug: corrects existing CLI behavior, including installation, update checks, source parsing, agent detection, or security checks.
   • enhancement: adds or intentionally expands CLI behavior, commands, agent support, or integration support.
4. If the patch is truncated, mixed, or insufficient to classify confidently, stop without adding a label. Do not infer a label from the title alone.
5. Use add_label once, with the triggering pull request number and the chosen label.