fix: move withdrawal commission deduction from application to approval

- commissionWithdrawLogic: remove upfront commission deduction;
  balance check now includes sum of all pending withdrawals to prevent
  double-spending; transaction only creates the withdrawal record (status=0)
- approveWithdrawal: add FOR UPDATE lock on user row, balance check before
  deducting, atomic commission decrement and commission log inside one
  transaction; clear user cache after commit
- rejectWithdrawal: remove commission refund and log — commission was never
  deducted on application under the new flow
- add migration 02150: refund commission for existing status=0 withdrawals
  that were deducted under the old logic; includes rollback script

Co-authored-by: multica-agent <github@multica.ai>

pkg/xerr/errMsg.go

@@ -46,6 +46,7 @@ func init() {
 		FamilyNotExist:                "家庭组不存在",
 		FamilyStatusInvalid:           "家庭组状态无效",
 		FamilyOwnerOperationForbidden: "家庭组所有者不允许此操作",
+		WithdrawalStatusInvalid:       "提现状态无效",
 
 		// Node error
 		NodeExist:         "Node already exists",