omd:add-reference — Core v2 catalog cutover gate

Status: CORE_V2_CATALOG_WRITE_BLOCKED.

This repository still reads the 440 historical reference files through the legacy frontmatter adapter. That makes them valid migration inputs, but it does not authorize a new legacy writer. Do not create, update, backfill, or sync a web/references/<id>/DESIGN.md from this skill.

When invoked: