기술 증명: 스캘핑 방지

function _update(
    address to,
    uint256 tokenId,
    address auth
) internal override returns (address) {
    address from = _ownerOf(tokenId);

    // 1. Allow Minting (Creation)
    if (from == address(0)) {
        return super._update(to, tokenId, auth);
    }

    // 2. Allow Burn (Destruction)
    if (to == address(0)) {
        return super._update(to, tokenId, auth);
    }

    // 3. Allow Refund (Return to Admin)
    if (to == owner()) {
        return super._update(to, tokenId, auth);
    }

    // 🛑 4. BLOCK ALL P2P TRANSFERS
    revert("P2P transfer is not allowed.");
}