feat(skill): add hugo event intake skill

[shunk031]

Summary

• add a repo-local hugo-event-intake skill for creating content/event entries from URLs or sparse notes
• add a deterministic helper with probe and write commands, duplicate detection, metadata extraction, and featured asset generation
• add regression tests for probe/write behavior and skill conventions

Testing

• uv run --with pytest pytest tests/test_hugo_event_intake.py
• uv run --with pyyaml python <skill-creator>/scripts/quick_validate.py .agents/skills/hugo-event-intake