Token-2022 Transfer-Fee Payment Reconciler

Recomputes the transfer fee a Token-2022 mint with the transfer-fee extension withholds and the net amount the recipient receives: given the fee schedule (older and newer authorities with their switch epoch), the TransferChecked amount, the execution epoch and the amount a payment verifier credited, it reports schedule, fee, net, the reconciliation verdict (MATCH, OVER_CREDITED, UNDER_CREDITED) and credited_minus_net. OVER_CREDITED with the fee as the difference reproduces the Kora GHSA-725g defect class: a facilitator crediting the pre-fee gross amount. All amounts are decimal strings computed in BigInt, no floats, and the informational consumer view shows where the x402 SVM gross-amount path and the balance-delta net path disagree.