Invoice statuses, void, and bad debt

Invoices move Draft → Unpaid → Partial → Paid, with Overdue applied automatically once the due date passes with a balance remaining.

Void cancels a sent invoice that should never have gone out. It's only allowed while the balance is fully unpaid — anything already collected has to be refunded first. A voided invoice drops out of every outstanding-balance total immediately. A *draft* with the same mistake can simply be deleted; deleting a sent invoice isn't allowed, so a paid invoice can never quietly vanish.

Bad debt is for real work that's genuinely never getting paid — a customer who's gone out of business or is unreachable after repeated follow-up. It writes off the entire remaining balance in one action, removing it from outstanding AR while keeping whatever was already collected intact, with an optional reason recorded. The invoices list carries a running Bad debt tile so written-off value stays visible rather than disappearing.

Reopen undoes either one. Reopening a fully paid invoice shows it as whatever it actually is right now — Partial, Unpaid, or Overdue if its due date has passed — rather than parking it back in Draft. Whatever was already collected stays untouched.

Once an invoice has received any payment it locks against line-item edits until that payment is voided. Void and bad-debt invoices lock the same way until reopened.