Repo had no SECURITY.md; adds one with a reachable contact address,
canonical repository URL, response process, and a version-support
table matching the actual 0.1.0 release line.
Co-Authored-By: Claude Sonnet 5 <noreply@anthropic.com>
Claude-Session: https://claude.ai/code/session_01AX8SWgnoExWzZFKsxpg5N4