Agent Skills: fix-git-history

Rewrite poor git commit messages into a clear conventional-commit history. Reads the last N commits with their diffs, proposes a clean conventional message for each by reading what the code actually changed, then opens a light-theme review UI where the user approves all or each message individually before the history is rewritten. Use when the user runs /fix-git-history or asks to clean up, rewrite, normalize, or fix commit messages or git history into a conventional-commit format.