docs: publish current task validation error contracts
Publish the corrected task-create/update error reference from actual Marketing #223, merged as bb2b54afa2e5d5532465a7de314356fd0d30744a. Developers now get the existing API's text error and optional field path, with malformed-JSON and wrong-type examples. The maintained source pins actual API #1101 e47d32e6051150d6af45c6f5df25bade0cba8891; separate schedule-syntax work is outside this publication.
Only the Releases specification, complete AI reference and provenance record change. All 243 managed paths verify against actual Marketing; 241 remain byte-identical, as do navigation, host settings and task wrappers. The complete reference retains 240 documents, 215 operation identities and 237 valid JSON blocks; only task-create/update bodies change.
Validation: actual-source and self-pin checks, full content/hash/navigation comparison and whitespace checks pass. Source tests and normal deployments are not hosted task/customer verification. Coordinator owns final merge; normal retained-host publication will be checked afterward. Related: recoupable/mono#318 and recoupable/mono#360.
Summary by cubic
Publishes the current task-create/update validation error contracts in the API reference so docs match the actual Marketing API behavior.
The 400 response now documents that malformed JSON returns only status and error (Invalid JSON body), while schema validation failures also include missing_fields with the JSON path of the first issue. Both cases get added examples, and missing_fields is no longer required on the UpdateTaskValidationErrorResponse schema.
Only api-reference/openapi/releases.json, llms-full.txt, and SOURCE-PROVENANCE.json change; the other 241 managed paths stay byte-identical, and the provenance source pins to the merged Marketing commit.
Related: recoupable/mono#318 and recoupable/mono#360.