Independently replace current FX authority without changing bank account identity or clearing a pause

Fresh treasury checker and operations:approve must independently approve exact replacement terms against the current authority digest. Actual correspondent identity, account and currency remain immutable. Limits, short-dated operating authority and public receipt keys can renew; the pause remains in force. Unsent orders bound to earlier authority require cancellation and a new proposal. Already dispatched money still requires an exact final receipt signed by a currently approved key; a rotated-out key cannot authorize new evidence. Previously accepted receipts retain the exact verified key/digest and remain recoverable without re-signing or moving money twice.