Incoming trade inbox API

The full contract now lives in Incoming trade API reference, alongside trade context, scoring and outgoing approval.

Outgoing proposal approval accepts {approved_by, message?} at POST /v1/trade/offers/{offer_key}/approve. A changed message creates a new offer_key, returned in the receipt, and supersedes the staged draft. Text must contain a non-whitespace character and be at most 1000 characters; exact text is preserved. Missing, null or unchanged text keeps existing approval behavior. Repeating an edited approval returns 200 with duplicate: true; a different edit after approval returns 409.

GET /v1/trade/offers includes drafted_message and message_edited (null/false for unedited offers). Edited offers retain the generated draft and identify the editor in approval.approved_by. evaluation.pitch remains generated evidence; human-edited messages are not checked against score evidence. See outgoing approval for transaction, retry and publication details.