Fix fee options for undeployed wallets

[corbanbrook]

Root cause: RpcRelayer.feeOptions was ignoring the caller’s to and always sending to =
wallet with raw encoded calls, which matches the failing request.

Changes made:

• Added Wallet.buildFeeOptionsTransaction() in wallet-core to build the correct fee-
  options target/data.
• For undeployed wallets, it targets the guest module and prefixes the wallet deploy
  call before wallet.execute.
• Updated WDK transactions.define() to pass that built target/data into relayer fee
  options.
• Updated dapp-client fee options to pass the already built signed transaction data.
• Updated relayer fee-options API to accept optional prebuilt calldata and stop
  overwriting to.
• Added focused tests for core transaction construction and relayer request body
  behavior.