Add wrap-up session skill

[spences10]

Summary

Add a /wrap-up skill for session lifecycle management. No equivalent exists in the toolkit currently.

What it does

End-of-session checklist:

• git status — uncommitted changes?
• Run tests on changed files
• Summarize what was accomplished
• Prompt for learnings (feed into /reflect)
• Note what's next / blockers for next session

Why

Sessions end abruptly. Learnings get lost, uncommitted work gets forgotten, next session starts cold. A wrap-up ritual captures state before context resets.

Prior art

• pro-workflow's wrap-up skill: https://github.com/rohitg00/pro-workflow/tree/main/skills/wrap-up
• Boris Cherny's workflow pattern of capturing learnings at session boundaries

Notes

• Should integrate with existing reflect skill (wrap-up prompts for learnings → reflect persists them)
• Keep it lightweight — checklist, not ceremony