Pure-JS deep-merge of two OpenAPI 3.0 documents. Unions paths and
components by key; throws on collisions. Public document's info,
servers, and root security win over the admin document's. Used by
dump-spec.ts to produce a single merged JSON for openapi-typescript.
Co-Authored-By: Claude Opus 4.7 (1M context) <noreply@anthropic.com>
