Move Issue #15 from TODO.md to COMPLETED_ISSUES.md
Issue #15 (Add Security Testing) was completed in v1.2.0 but was
left in TODO.md instead of being properly archived to COMPLETED_ISSUES.md.
Changes:
- Moved Issue #15 from TODO.md to COMPLETED_ISSUES.md
- Added comprehensive details about the 22 security tests implemented
- TODO.md now correctly shows Issues #16-18 as remaining low-priority items
- COMPLETED_ISSUES.md now has Issue #15 at the top as the most recent completion
This completes the documentation cleanup for the v1.2.0 release.
๐ค Generated with [Claude Code](https://claude.com/claude-code)
Co-Authored-By: Claude <noreply@anthropic.com>