feat: add ontology-and-logic-audit skill

[iqdoctor]

Summary

• add a new ontology-and-logic-audit skill
• keep the skill body tightly aligned with the original Greek-scholastic reasoning prompt rather than expanding it into a larger workflow document
• add the new skill to the human-facing README index

Notes

• the skill is intentionally compact and instruction-shaped
• I intentionally left the generated docs/skills.json update out of this PR because that repository index drift is handled separately in docs: regenerate skills index #8

Testing

• reviewed the final SKILL.md against the source prompt to keep the guidance aligned