Agent Skills: handoff

Write a structured handoff document so a fresh Claude Code session can continue the current work without re-reading the entire transcript. Use when asked to "hand off", "handoff", run "/handoff", prepare for a "/clear", start a fresh session without losing context, or save the current conversation's state for a future session. Produces a local `HANDOFF_<slug>.md` (or `/tmp/HANDOFF_<slug>.md` outside a repo) that the user pastes or opens in the new session.