chore: add pre-commit hook and update review skill to mirror GitHub CI

.githooks/pre-commit runs bash syntax check, shfmt format check,
shellcheck, and go vet against staged files on every commit.
Catches the same issues as check.yml before they reach GitHub.

Also update CONTRIBUTING.md setup instructions to include
`git config core.hooksPath .githooks`.

CONTRIBUTING.md

@@ -8,6 +8,9 @@ brew install shfmt shellcheck bats-core golangci-lint
 
 # Install goimports for better Go formatting
 go install golang.org/x/tools/cmd/goimports@latest
+
+# Install pre-commit hook (runs format/lint checks on every commit)
+git config core.hooksPath .githooks
 ```
 
 ## Development