Add /handoff <goal>: compaction-aware branch summary, editable generated prompt, new child session with the prompt in the editor.
Generation prompt references artifacts by path or URL, redacts secrets and PII, and adds a Suggested skills section.
# Changelog
## Unreleased
- Add `/handoff <goal>`: compaction-aware branch summary, editable generated prompt, new child session with the prompt in the editor.
- Generation prompt references artifacts by path or URL, redacts secrets and PII, and adds a `Suggested skills` section.