Boulevard Client API - Catalog & Availability
Public-facing catalog reads that power a booking widget before a client ever creates a cart - business and location lookup, bookable service categories, staff/professional listings, and bookable dates/times for a chosen service and location. Mirrors the `book-sdk` modules `Businesses`, `Locations`, `Services`, `Staff`, and the cart's `getBookableDates` / `getBookableTimes` calls.