- Create .opencode/rules/no-duplicate-ontology-mappings.md with detection script
- Add Rule 52 to AGENTS.md (after Rule 51)
- Fix 29 duplicate mappings: same URI in multiple mapping categories
- 26 slot files: remove duplicates keeping most precise mapping
- 3 class files: ExhibitionSpace, Custodian, DigitalPlatform
- Mapping precedence: exact > close > narrow/broad > related
Each ontology URI must appear in only ONE mapping category per schema
element, following SKOS semantics where mapping properties are mutually
exclusive.
