docs: drop removed OpaqueProvider from AttestationUnsupported row

docs/spec/error-codes.md

@@ -24,7 +24,7 @@ An error also carries a human-readable message and an optional `detail`. The mes
 | `RevocationStatusUnknown` | `REVOCATION_STATUS_UNKNOWN` | 503 | The verifier set `max_revocation_staleness` and has no revocation snapshot, or its snapshot's `as_of` is older than that bound at the evaluation time. Nothing is wrong with the chain; the verifier cannot currently establish that it has not been revoked, and fails closed. Raised by `verify_chain`. |
 | `InvalidRevocation` | `INVALID_REVOCATION` | 400 | A revocation statement or snapshot is malformed, unsigned, or carries a signature that does not verify, or a snapshot file is missing or not valid JSON. A snapshot with any such statement is refused as a whole. Raised by `RevocationStatement`, `RevocationSnapshot` and `load_revocation_snapshot`. |
 | `HolderProofInvalid` | `HOLDER_PROOF_INVALID` | 401 | The presenter of a delegation chain did not prove it controls the leaf `subject`: no proof was presented, the proof was malformed, it answered a challenge this callee did not issue or which has expired, or its signature did not verify over the exact request being made. 401 rather than 403 because the chain may well carry the authority requested while the caller has not shown it is the party that authority was delegated to. Distinct from `ATTESTATION_FAILED`, which is about what the caller is *running*: a caller can appraise perfectly and still fail this. Raised by `verify_holder_proof`, `handle_peer_request`, and the A2A adapter on a malformed proof. See [profile](profile.md) P-4a. |
-| `AttestationUnsupported` | `ATTESTATION_UNSUPPORTED` | 500 | An attestation provider was requested that the host cannot supply. Raised by any provider's `attest` when the host lacks what its collector needs, and by `OpaqueProvider`, which has no collector. The `detail` names the missing piece. See [Peer Attestation](attestation.md). |
+| `AttestationUnsupported` | `ATTESTATION_UNSUPPORTED` | 500 | An attestation provider was requested that the host cannot supply. Raised by any provider's `attest` when the host lacks what its collector needs. The `detail` names the missing piece. See [Peer Attestation](attestation.md). |
 | `AttestationFailed` | `ATTESTATION_FAILED` | 412 | Attestation evidence was present but did not verify. Raised by the SEV-SNP verifier on a malformed report, an untrusted or broken certificate chain, a bad report signature, or a measurement / report-data mismatch. See [Peer Attestation](attestation.md). |
 | `SealedChannelError` | `SEALED_CHANNEL_ERROR` | 500 | The sealed peer channel could not construct or open a payload: an invalid peer public key, a malformed or unsupported sealed blob, a wrong key, or a tampered ciphertext (AEAD authentication failure). Fails closed; never returns unauthenticated plaintext. See [Sealed Channel](sealed-channel.md). |
 | `ProvenanceLinkBroken` | `PROVENANCE_LINK_BROKEN` | 409 | A `DelegationRecord` does not chain to its stated parent record, or a record was tampered with so its hash no longer matches a child's link: empty provenance chain, duplicate `record_id`, a root record that references a parent, a broken parent hash link, or a record whose `credential_id` or subject does not match the chain. Raised by `verify_dag` and `cross_check_chain`. |