Add customer-facing booking flow with three public API endpoints
(/api/book/services, /api/book/availability, /api/book/appointments)
and a four-step React wizard (service → date/time → contact info → confirm).
Availability is computed from real groomer schedules with slot-level
conflict detection. Booking auto-creates or matches clients by email
and uses a transaction to guard against race conditions.
Co-Authored-By: Paperclip <noreply@paperclip.ing>
Groom Book CTO