Generates and formats git commit messages following the Conventional Commits specification. Use when the user asks for help writing commit messages, formatting git commits, wants to write a commit msg for staged changes, needs to produce a changelog entry, or mentions conventional commits, semantic versioning, or version bumps. Analyzes diffs or change descriptions, selects the correct type/scope, writes an imperative-mood header under 72 characters, and composes optional body and footer sections including breaking-change notation.