Setup Git Hooks

Scaffold a repo-local git hooks system (plain bash hooks + make setup, shared common.sh library, optional per-worktree isolation):

hooks/
├── common.sh           # shared logging and validation functions
├── install-hooks.sh    # symlinks hooks to .git/hooks/
├── commit-msg.sh       # validate commit message format
├── pre-commit.sh       # staged-file checks (format, whitespace)
├── pre-push.sh         # full CI checks (lint, test)
├── post-checkout.sh    # auto-update hooks + deps on branch switch
├── post-merge.sh       # auto-update hooks + deps on merge
└── post-rewrite.sh     # auto-update hooks on rebase/amend

This is a prompt-driven skill, not a deterministic script. Explore, present what you found, confirm with the user, then scaffold.