Facility booking-mode redesign, multi-plan subscriptions, and Classes

Implements the facility-classes-booking-dashboard plan (backend):

- Facility.BookingMode (single Scheduled/AdHoc choice) replaced with
  independent SupportsClasses/SupportsBooking flags, so one facility
  can run a class and accept walk-in bookings; a running class now
  blocks walk-in booking for its window on both create and reschedule.
- CustomerPlan.GrantsGymAccess + CustomerPlanClass join table let a
  customer hold one gym-access plan plus any number of class-only
  plans. Replaced the old single-subscription resolution
  (GetActiveSubscriptionByCustomerId/HasAnyActiveSubscriptionAsync)
  with gym-access-aware and class-aware resolvers across booking
  creation/cancellation, plan assignment, and customer self-service.
  Fixed ChangeMembershipPlan/renewal plan-changes, which resolved "the
  subscription to replace" by most-recent-created and would have
  deactivated a member's class subscription instead of their gym one.
- New FacilityClass model: recurring class definitions (Daily/Weekly/
  Monthly/Custom) with lazy occurrence generation (8-week horizon,
  race-safe via a unique index) and proper unlimited-capacity handling.
  "Mark not held" replaces the old bare-cancel: cascades to cancel and
  refund every confirmed booking on the occurrence through the same
  core CancelBooking uses, and frees the slot for walk-in booking.
  Scheduling conflicts (a walk-in booking now overlapping a class) are
  surfaced for staff to resolve via the existing Reschedule flow.
- Renamed the pre-existing "AdHoc" booking-mode terminology to
  "WalkIn" throughout (routes, methods, DTOs, the stored BookingMode
  value) for a clearer, simpler name.

Co-Authored-By: Claude Sonnet 5 <noreply@anthropic.com>

Interfaces/Services/IBookingService.cs

@@ -1,21 +1,25 @@
+using Fitness_core_BE.Models;
 using Microsoft.AspNetCore.Http;
 
 namespace Fitness_core_BE.Interfaces.Services
 {
     public interface IBookingService
     {
+        /// <summary>Shared cancel+refund core -- see BookingService.CancelBookingCore.</summary>
+        Task CancelBookingCore(Booking booking);
+
         /// <summary>Logged-in member books a session against their own plan's allowance.</summary>
         Task<object> CreateMemberBooking(object payload, HttpContext httpContext);
 
         /// <summary>No membership at all -- pay-per-session, identity proof is the returned OTP.</summary>
         Task<object> CreateGuestBooking(object payload, HttpContext httpContext);
 
-        /// <summary>Member books an AdHoc-mode facility directly for an arbitrary time window, no
+        /// <summary>Member books a WalkIn-mode facility directly for an arbitrary time window, no
         /// pre-created session.</summary>
-        Task<object> CreateMemberAdhocBooking(object payload, HttpContext httpContext);
+        Task<object> CreateMemberWalkInBooking(object payload, HttpContext httpContext);
 
-        /// <summary>Guest/staff walk-in books an AdHoc-mode facility directly.</summary>
-        Task<object> CreateGuestAdhocBooking(object payload, HttpContext httpContext);
+        /// <summary>Guest/staff walk-in books a WalkIn-mode facility directly.</summary>
+        Task<object> CreateGuestWalkInBooking(object payload, HttpContext httpContext);
 
         /// <summary>Renders the public, unauthenticated confirmation page a booking's ShareUrl
         /// points to -- the "copy the link and share it" receipt. Returns null if not found, so
@@ -36,7 +40,7 @@ namespace Fitness_core_BE.Interfaces.Services
         /// no cancel/recreate needed. Guest bookings only.</summary>
         Task<object> ReassignBooking(object payload, HttpContext httpContext);
 
-        /// <summary>Staff moves a Confirmed booking to a different time (AdHoc) or session
+        /// <summary>Staff moves a Confirmed booking to a different time (WalkIn) or session
         /// (Scheduled), only onto a slot with room.</summary>
         Task<object> RescheduleBooking(object payload, HttpContext httpContext);
 

Interfaces/Services/IClassService.cs

@@ -0,0 +1,18 @@
+namespace Fitness_core_BE.Interfaces.Services
+{
+    public interface IClassService
+    {
+        Task<object> GetFacilityClasses(object payload, HttpContext httpContext);
+        Task<object> CreateFacilityClass(object payload, HttpContext httpContext);
+        Task<object> UpdateFacilityClass(object payload, HttpContext httpContext);
+        Task<object> GetOccurrences(object payload, HttpContext httpContext);
+        Task<object> GetSchedulingConflicts(object payload, HttpContext httpContext);
+
+        /// <summary>Lazy occurrence generation, mirroring the existing SweepOverdueBookingsAsync
+        /// convention (no background job) -- generates the missing FacilitySession rows up to
+        /// "today + 8 weeks" for every active, non-Custom class whose watermark hasn't reached
+        /// it yet, and advances the watermark. Called from the top of FacilityService.GetSessions,
+        /// the one read path everything already goes through.</summary>
+        Task EnsureOccurrencesGeneratedAsync(Guid clientId);
+    }
+}