Cancel all resting orders for an account in a specific market.

Prerequisites: same as POST /v1/orders/place — EIP-712 domain, nonce state, and the router address from GET /v1/system/config.

Action hash:

actionHash = keccak256(abi.encode(
  keccak256("RISE_PERPS_CANCEL_ALL_ORDERS_V1"),  // bytes32 action selector
  uint256(marketId)))

Permit digest (EIP-712):

VerifyWitness(address account,address target,bytes32 hash,uint48 nonceAnchor,uint8 nonceBitmap,uint32 deadline)

hash = actionHash, target = RISExUniversalRouter address (NOT the OrdersManager, NOT the account, NOT the domain verifyingContract).

Signature: 64-byte EIP-2098 compact (r + yParityAndS) or 65-byte (r+s+v, auto-converted). permit.signature is a protobuf bytes field — send it base64 over REST, not 0x hex.