Past dates visually unselectable and rejected client-side before API call

Clickable past dates send doomed POST requests to the booking API, wasting backend cycles, polluting logs with 4xx errors, and surfacing generic server-side failures that erode user trust. Customers who manage to submit a past date hit a confusing rejection screen mid-flow, abandon the booking, and never return. This is a preventable user-experience regression that also inflates telemetry noise and masks real availability failures in your error-rate dashboards.

In your calendar slot component, compute isPast from new Date(slot.time) < new Date() once per render, then apply both a disabled attribute and a visually distinct class (opacity-50 cursor-not-allowed) when true. Short-circuit the click handler before any fetch call fires. See src/components/CalendarSlot.tsx:

const isPast = new Date(slot.time) < new Date()
if (isPast) { toast.error('This date has passed'); return }