New CLI tool that mirrors a Gitea release (with assets) to a GitHub
repository. Replaces the 40-line inline bash in auto-release.yml Step 9.
Supports create/update, asset download+upload, and proper GitHub API
headers (User-Agent, Accept).
Closes#160
Authored-by: Moko Consulting
Co-Authored-By: Claude Opus 4.6 (1M context) <noreply@anthropic.com>