feat(skills): add autonomous Go agent skill
Adds /go-agent skill for continuous Go development:
- Finds open issues in host-uk/core repo
- Creates branches, implements solutions, writes tests
- Uses Task runner (task test, task lint, etc.)
- Handles CodeRabbit reviews automatically
- Merges when approved
- Loops to pick up next task
Go-specific features:
- Error handling patterns with errors.E
- Test naming conventions (_Good, _Bad, _Ugly)
- i18n string management
- Package reference for core CLI
Co-Authored-By: Claude Opus 4.5 <noreply@anthropic.com>