EVM: the LifiIntentsBridge contract address (the transaction to). Solana: the lifi-intents-bridge program id
EVM: 0x-prefixed calldata of the bridge / bridgeNative call.
Solana: base64 of the unsigned v0 VersionedTransaction (fee payer = sender, a fresh blockhash: sign at once)
Integer native value to attach: amountIn in the smallest units for a native source token, "0" otherwise
(always "0" on Solana)
The ready-to-sign transaction of a LI.FI Intents order, as served by the Core API