Add Booking module: model, create/read/cancel API, Filament resource (T4.1-T4.7)

- Booking model with booking_vehicle_options line items (supports mixing
  vehicle options like front_seat + back_seat in one booking), price
  snapshot, status machine, and driver/car assignment fields
- BookingService: front-seat max, disabled-option toggles, duplicate-option
  and whole-vehicle-exclusivity guards
- CreateBookingAction, CancelBookingAction, AssignDriverAction
- BookingRefGenerator: sequential EVB-AAAAA1-style refs via row lock
- POST/GET/cancel booking API endpoints (Sanctum, ownership + admin policy)
- BookingPlugin + Filament BookingResource: list, detail view, Cancel and
  Assign Driver actions (shared between table and detail page)
- domain.md updated for multi-vehicle-option bookings (§2) and driver/
  vehicle assignment (§5a)

app-modules/booking/src/Exceptions/DriverAssignmentNotAllowedException.php

@@ -0,0 +1,27 @@
+<?php
+
+namespace Modules\Booking\Exceptions;
+
+use Illuminate\Http\JsonResponse;
+use Illuminate\Http\Request;
+use Modules\Booking\Models\Booking;
+use RuntimeException;
+
+class DriverAssignmentNotAllowedException extends RuntimeException
+{
+    public static function notConfirmed(Booking $booking): self
+    {
+        return new self(
+            "Booking [{$booking->booking_ref}] cannot have a driver assigned because its status is [{$booking->status->value}], not confirmed."
+        );
+    }
+
+    public function render(Request $request): ?JsonResponse
+    {
+        if ($request->expectsJson()) {
+            return response()->json(['message' => $this->getMessage()], 422);
+        }
+
+        return null;
+    }
+}