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>

Repos/FacilityClassRepository.cs

@@ -0,0 +1,132 @@
+using Fitness_core_BE.Interfaces;
+using Fitness_core_BE.Models;
+using Microsoft.EntityFrameworkCore;
+
+namespace Fitness_core_BE.Repos
+{
+    public class FacilityClassRepository : IFacilityClassRepository
+    {
+        private readonly TenantDbContext _context;
+
+        public FacilityClassRepository(TenantDbContext context)
+        {
+            _context = context;
+        }
+
+        public async Task<FacilityClass> CreateFacilityClass(FacilityClass facilityClass)
+        {
+            facilityClass.FacilityClassId = Guid.NewGuid();
+            facilityClass.CreatedAt = DateTime.UtcNow;
+            facilityClass.IsActive = true;
+
+            _context.FacilityClasses.Add(facilityClass);
+            return facilityClass;
+        }
+
+        public async Task<List<FacilityClass>> GetFacilityClasses(Guid clientId, bool includeInactive = false)
+        {
+            var query = _context.FacilityClasses
+                .Include(fc => fc.Facility)
+                .Where(fc => fc.FKClientId == clientId);
+            if (!includeInactive)
+                query = query.Where(fc => fc.IsActive);
+
+            return await query.OrderBy(fc => fc.Name).ToListAsync();
+        }
+
+        public Task<FacilityClass?> GetFacilityClassById(Guid facilityClassId)
+            => _context.FacilityClasses
+                .Include(fc => fc.Facility)
+                .FirstOrDefaultAsync(fc => fc.FacilityClassId == facilityClassId);
+
+        public async Task<FacilityClass> UpdateFacilityClass(FacilityClass facilityClass)
+        {
+            var existing = await _context.FacilityClasses.FindAsync(facilityClass.FacilityClassId)
+                ?? throw new KeyNotFoundException("Class not found");
+
+            existing.Name = facilityClass.Name;
+            existing.Description = facilityClass.Description;
+            existing.RecurrenceType = facilityClass.RecurrenceType;
+            existing.StartTimeOfDay = facilityClass.StartTimeOfDay;
+            existing.DurationMinutes = facilityClass.DurationMinutes;
+            existing.WeekDaysMask = facilityClass.WeekDaysMask;
+            existing.MonthDays = facilityClass.MonthDays;
+            existing.SeriesStartDate = facilityClass.SeriesStartDate;
+            existing.SeriesEndDate = facilityClass.SeriesEndDate;
+            existing.Capacity = facilityClass.Capacity;
+            existing.IsUnlimitedCapacity = facilityClass.IsUnlimitedCapacity;
+            existing.IsActive = facilityClass.IsActive;
+            existing.OccurrencesGeneratedThrough = facilityClass.OccurrencesGeneratedThrough;
+
+            return existing;
+        }
+
+        public Task<List<FacilityClass>> GetClassesNeedingGenerationAsync(Guid clientId, DateTime horizon)
+            => _context.FacilityClasses
+                .Where(fc => fc.FKClientId == clientId && fc.IsActive && fc.RecurrenceType != "Custom"
+                    && fc.OccurrencesGeneratedThrough < horizon)
+                .ToListAsync();
+
+        public async Task<HashSet<DateTime>> GetExistingOccurrenceStartTimesAsync(Guid facilityClassId, DateTime from, DateTime to)
+        {
+            var times = await _context.FacilitySessions
+                .Where(s => s.FKFacilityClassId == facilityClassId && s.StartTime >= from && s.StartTime < to)
+                .Select(s => s.StartTime)
+                .ToListAsync();
+            return times.ToHashSet();
+        }
+
+        public async Task AddOccurrencesAsync(IEnumerable<FacilitySession> occurrences)
+        {
+            var list = occurrences.ToList();
+            foreach (var occurrence in list)
+            {
+                occurrence.FacilitySessionId = Guid.NewGuid();
+                occurrence.CreatedAt = DateTime.UtcNow;
+                occurrence.IsCancelled = false;
+            }
+            await _context.FacilitySessions.AddRangeAsync(list);
+        }
+
+        public Task<List<FacilitySession>> GetOccurrencesForClassAsync(Guid facilityClassId, bool includeCancelled)
+        {
+            var query = _context.FacilitySessions.Where(s => s.FKFacilityClassId == facilityClassId);
+            if (!includeCancelled)
+                query = query.Where(s => !s.IsCancelled);
+
+            return query.OrderByDescending(s => s.StartTime).ToListAsync();
+        }
+
+        public async Task<int> DeleteFutureUnbookedOccurrencesAsync(Guid facilityClassId, DateTime nowUtc)
+        {
+            var candidates = await _context.FacilitySessions
+                .Where(s => s.FKFacilityClassId == facilityClassId && s.StartTime > nowUtc)
+                .Where(s => !_context.Bookings.Any(b => b.FKFacilitySessionId == s.FacilitySessionId))
+                .ToListAsync();
+
+            _context.FacilitySessions.RemoveRange(candidates);
+            return candidates.Count;
+        }
+
+        public async Task LinkPlanToClassAsync(Guid customerPlanId, Guid facilityClassId)
+        {
+            _context.CustomerPlanClasses.Add(new CustomerPlanClass
+            {
+                CustomerPlanClassId = Guid.NewGuid(),
+                FKCustomerPlanId = customerPlanId,
+                FKFacilityClassId = facilityClassId
+            });
+        }
+
+        public Task<List<Booking>> GetSchedulingConflictsAsync(Guid clientId)
+        {
+            return _context.Bookings
+                .Include(b => b.Facility)
+                .Where(b => b.FKClientId == clientId && b.FKFacilitySessionId == null && b.Status == "Confirmed")
+                .Where(b => _context.FacilitySessions.Any(s =>
+                    s.FKFacilityId == b.FKFacilityId && s.FKFacilityClassId != null && !s.IsCancelled &&
+                    s.StartTime < b.EndTime && s.EndTime > b.StartTime))
+                .ToListAsync();
+        }
+    }
+}