Commit the current staged changes.

1. Run git diff --staged. If empty, tell the user there is nothing staged and stop.
2. Run git log --oneline -5 to understand this repo's commit message style.
3. Run git branch --show-current to get the branch name. If it contains a CM-XXX ticket number, include it at the end of the subject in parentheses (e.g. feat: add token refresh (CM-1234)).
4. Generate a single commit message following Conventional Commits format: type: description. Subject max 72 characters. No scope required unless meaningful. No body, no extra trailers, no Co-Authored-By. (The Signed-off-by trailer is added automatically by -s.)
   • Valid types: feat, fix, docs, style, refactor, perf, test, build, ci, chore, revert
5. Run git commit -s -S -m "<message>" using exactly the generated message.
6. Output only the commit hash and subject line from the result.