chore: add mise tasks, update git-workflow skill, and rewrite CLAUDE.md

[zawakin]

Summary

• Add mise.toml and tasks.toml with 19 tasks: cargo (build, test, fmt, clippy, verify, snapshot:accept), lab (grep), release (dry-run, execute, changelog), git workflow (home, new, cleanup, status, pause, abandon, undo, sync, open-pr)
• Rewrite git-workflow skill to use mise run git:* tasks with proactive workflow, stacked PRs, and yak shaving protocol
• Rewrite CLAUDE.md in web-style: Required section, Quick Reference, Skills table, duplicated content blocks for reinforcement
• Reverse AGENTS.md symlink direction (AGENTS.md -> CLAUDE.md)

Test plan

• mise tasks lists all 19 tasks
• All skills recognized by Claude Code after changes

🤖 Generated with Claude Code

[SURO612]

こんなにできないのでへらしてもらえませんか？(まだ12歳)