description: Generate a commit message from staged changes

Generate a commit message from the staged changes (git diff --cached).

Format:

:

Rules:

• type: One of feat, fix, docs, style, refactor, perf, test, chore
• Subject: 50 chars max, imperative mood, no ending period, capitalize first letter
• Body: Cohesive paragraph or bullet points. Past tense. State what and why only (no how). Wrap at 72 chars.
• Follow Conventional Commits 1.0.0
• Skip obvious or minor changes in the body
• Insert blank line between subject and body

Output the commit message only — no extra text.