feat: add transaction data to required assets button

[matthewwalsh0]

Add dummy transaction data to Send Calls - Required Assets button.

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Note

Low Risk
Low risk: only adjusts the demo request payload for a single button click handler, with no changes to signing, balances, or validation logic.

Overview
The Send Calls - Required Assets button now submits a call that includes dummy data (test(uint256) with value 123) instead of a plain value-only call.

The required USDC auxiliaryFunds.requiredAssets capability is unchanged; this just expands the example request to cover calldata-enabled transactions.

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