The server binds inference_provider and inference_model into the canonical
payload. buildSignable knew 8 and 10 field shapes, so it rebuilt 10 against a
twelve-field proof and reported a genuine proof as unsigned. Conditional, so
older proofs canonicalise byte-identically.

The harness hardcoded seven cases and kept reporting green after the contract
gained conf_h and conf_i. Now fetches /conformance/cases, and fails if the
server returns none or if no case verifies true.

9/9 including conf_h_model_bound and conf_i_model_stripped.