Payments often arrive before they are recorded, so stamping paid_at
with the click time skews received-per-month and days-to-pay stats.
Mark paid now takes an optional date, and a paid invoice gets a form
to correct it. Past days are stored at 12:00 UTC so the date holds in
any timezone; future and malformed dates are refused. The PDF does not
print the date, so nothing is re-rendered.
Assisted-by: Claude:opus-5-5
Claude-Session: https://claude.ai/code/session_01TCc5TvWnAs5xPvGMQXTJw3
Sergei Poljanski
9d88b8af8f