feat: Enhance booking functionality with invoice management and dashboard summary

- Added customerId to guest booking requests for better identification.
- Implemented new endpoints for managing booking invoices and dashboard summaries.
- Created BookingInvoice and BookingDashboardSummary DTOs to support new features.
- Updated Booking and BookingInvoice models to include payment method and timestamps.
- Enhanced BookingService to handle invoice creation upon payment confirmation.
- Modified BookingRepository to support CRUD operations for BookingInvoice.
- Updated TenantDbContext to include BookingInvoice DbSet and relevant configurations.
- Improved error handling and validation for booking completion and payment processes.

Models/Booking.cs

@@ -86,24 +86,34 @@ namespace Fitness_core_BE.Models
         public string PaymentStatus { get; set; } = "NotRequired";
         public decimal AmountCharged { get; set; } = 0m;
 
+        /// <summary>"Cash" | "Bank" -- set alongside PaymentStatus becoming "Paid" (MarkGuestBookingPaid
+        /// or the Complete checkout flow). Null until then.</summary>
+        [MaxLength(20)]
+        public string? PaymentMethod { get; set; }
+        /// <summary>Set the moment PaymentStatus becomes "Paid" -- distinct from BookedAt/CheckedOutAt,
+        /// this is specifically when the money was recorded, used to bucket booking revenue into
+        /// Profit &amp; Loss and to date-stamp the BookingInvoice snapshot.</summary>
+        public DateTime? PaidAt { get; set; }
+
         // Set only once payment is confirmed for a pay-per-session guest booking, or
         // immediately for a member session (no payment gate) -- see PaymentStatus.
         public Guid? FKPaymentTransactionId { get; set; }
         [ForeignKey(nameof(FKPaymentTransactionId))]
         public PaymentTransaction? PaymentTransaction { get; set; }
 
-        /// <summary>"Confirmed" | "CheckedIn" | "Cancelled" | "NoShow" | "Completed". NoShow and
-        /// Completed are reached either by explicit staff action (MarkNoShow/Complete) or lazily,
-        /// swept by BookingService.SweepOverdueBookingsAsync at the top of every check-in call
-        /// (not a background job -- overdue bookings are reconciled the next time any check-in
-        /// happens for this client, across every facility).</summary>
+        /// <summary>"Confirmed" | "CheckedIn" | "Cancelled" | "NoShow" | "Completed". NoShow is
+        /// reached either by explicit staff action (MarkNoShow) or lazily, swept by
+        /// BookingService.SweepOverdueBookingsAsync at the top of every check-in or checkout call
+        /// (not a background job -- overdue Confirmed bookings are reconciled the next time any
+        /// check-in/checkout happens for this client, across every facility). Completed is
+        /// reached ONLY by the explicit Complete action -- a guest booking can't reach it while
+        /// still Unpaid, so there's no automatic path that would check someone out unpaid.</summary>
         public string Status { get; set; } = "Confirmed";
 
         public DateTime BookedAt { get; set; } = DateTime.UtcNow;
         public DateTime? CheckedInAt { get; set; }
-        /// <summary>Set when the booking reaches Completed, whether via the manual Complete
-        /// action or the lazy overdue-sweep -- the actual moment it was reconciled, not
-        /// necessarily EndTime.</summary>
+        /// <summary>Set when the booking reaches Completed via the manual Complete action -- the
+        /// actual moment it was checked out, not necessarily EndTime.</summary>
         public DateTime? CheckedOutAt { get; set; }
         public DateTime CreatedAt { get; set; } = DateTime.UtcNow;
     }