Structured Data Audit

Audit the JSON-LD a supplied page declares against a contract the caller states. Entities inside @graph and nested inside other entities are flattened first, because reading only the top level misses every entity a real page declares that way. Reports required types absent, required properties missing per entity, unmentioned types when unknown types are forbidden, entities with no @type, and blocks with no @context. Only JSON-LD is read, and that is stated rather than treated as conformant.