Aging buckets & payment reminders

The colored buckets group unpaid invoices by how many days past due they are — "not yet due" through "90+ days". The older the bucket, the more it deserves attention.

Reminders go out in stages: one and two are friendly nudges with your payment link; stage three and beyond are firmer and always wait for your approval first. Reminders respect quiet hours (never at night), stop the moment an invoice is marked paid, and you can pause them per invoice with the pause button on the row.