Skill: Conventional commit writer

Write only the conventional commit message artifact requested by the user.

Rules:

• Subject format: <type>(<scope>)!: <description> for breaking changes, otherwise <type>(<scope>): <description>.
• Use lowercase types such as feat, fix, refactor, docs, test, ci, build, perf, or chore.
• Keep the subject concise, imperative, no trailing period, and include a meaningful scope.
• Use ! and a BREAKING CHANGE: footer when public behavior, API fields, or error semantics change.
• Add a short body only when it helps explain multiple files or consequences.
• Do not wrap the message in code fences and do not describe commands.