Expose redeemed-vs-requested payout shortfall in withdrawal status

[marimes]

Context

Withdrawal execution now continues when redeemed amount is below requested payout and sends the redeemed amount instead of hard-failing.

Problem

Operators/users currently do not get explicit structured feedback that a shortfall happened (for example, requested 32100 vs redeemed 32099). This makes support/debugging harder.

Proposal

• Persist payout shortfall metadata on withdrawal rows (requested, redeemed, shortfall).
• Expose this in API response/timeline status for the withdrawal.
• Show a concise UI note in kiosk/operator panel when shortfall > 0.

Acceptance criteria

• shortfall values are queryable from API for completed withdrawals
• UI displays a non-alarming but explicit note when payout is less than requested
• logs still include the warning entry for operational tracing