feat: configurable business schedule (delivery/pickup/SMS days)
- New table business_schedule_settings (delivery_days, pickup_days, sms_days)
- RPC get_business_schedule() (public) + update_business_schedule() (admin)
- Admin UI: BusinessSchedulePanel with day pills for each category
- ClientDeliveryPage: fetches schedule, replaces hardcoded Sunday/weekend checks
- PickupSlotsPicker: uses pickupDays prop instead of hardcoded isWeekend
- Edge function confirm-delivery-choice: reads delivery_days from DB
- delivery-invitations.ts: buildDefaultDatedAvailableSlots reads delivery_days
- RPC confirm_delivery_choice_by_token: checks delivery_days instead of extract(dow)=0
- SMS scripts: get_sms_days() reads sms_days from business_schedule_settings
and overrides per-campaign work_days setting
- Nav item Расписание for mega_admin and admin roles
- Default: Mon-Fri (1,2,3,4,5) for all three categories