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/BookingPlugin.php

@@ -0,0 +1,38 @@
+<?php
+
+namespace Modules\Booking;
+
+use Filament\Contracts\Plugin;
+use Filament\Panel;
+
+class BookingPlugin implements Plugin
+{
+    public function getId(): string
+    {
+        return 'booking';
+    }
+
+    public function register(Panel $panel): void
+    {
+        $panel
+            ->discoverResources(
+                in: __DIR__.'/Filament/Resources',
+                for: 'Modules\Booking\Filament\Resources',
+            )
+            ->discoverPages(
+                in: __DIR__.'/Filament/Pages',
+                for: 'Modules\Booking\Filament\Pages',
+            )
+            ->discoverWidgets(
+                in: __DIR__.'/Filament/Widgets',
+                for: 'Modules\Booking\Filament\Widgets',
+            );
+    }
+
+    public function boot(Panel $panel): void {}
+
+    public static function make(): static
+    {
+        return app(static::class);
+    }
+}