Session Summary Generator

为Leavn工作生成全面的会话总结 - 提交、指标、成就、剩余工作、交付准备情况

Create session wrap-up:

Git stats:

git log --oneline --since="today"
git diff --shortstat {start-commit}

Count achievements:
- Files modified
- Lines added/deleted
- Bugs fixed
- Features completed
Create summary doc:
- SESSION_SUMMARY.md
- Commits list
- Metrics
- Achievements
- Next steps
- Ship readiness

Use when: Session ending, need summary, planning next work