Set an attendee's status from the admin edit form (a plain column write, outside the encrypted pii_blob). The outstanding balance is NOT set from the form — it projects from the transfers ledger, and an operator adjusts it through the ledger's manual write-off entries.

Every assignment uses a write transaction so it serialises with status deletion. When clearBalance is set, a stranded receivable is reconciled to 0 in that SAME transaction, so the two writes land atomically.