[Wise] Prevent submitting when org has insufficient funds

You should not be able to submit a Wise reimbursement when the org has insufficient funds. We should be able to at least guess based off of the estimated cost.

No file or test is named. Start by locating the Wise reimbursement submission flow and the logic that estimates reimbursement cost; trace how the organization's available funds are checked. Done means a reimbursement with an estimated cost above available funds cannot be submitted, with coverage for the insufficient-funds case.

Written by the indexing model from the issue text.