Generalize per-vehicle-option booking rules to Front Seat too

Front Seat previously had a hardcoded max-per-booking check with no enable
toggle; now every Vehicle Option (front_seat/back_seat/whole_vehicle) gets
the same config-driven pair — an on/off toggle and a max passenger_count —
surfaced via new BOOKING_*_ENABLED/BOOKING_*_MAX_PER_BOOKING env vars,
editable from ManageAppSettings, and exposed on route pricing as
max_per_booking.

app-modules/routing/tests/Feature/RoutesReadApiTest.php

@@ -37,6 +37,7 @@ test('searches active routes with nested company, destinations, time slots and p
         ->assertJsonPath('routes.data.0.time_slots.0.is_active', true)
         ->assertJsonPath('routes.data.0.pricing.0.vehicle_option', 'front_seat')
         ->assertJsonPath('routes.data.0.pricing.0.price', '12000.00')
+        ->assertJsonPath('routes.data.0.pricing.0.max_per_booking', config('booking.front_seat_max_per_booking'))
         ->assertJsonCount(0, 'return_routes.data');
 });
 
@@ -311,8 +312,17 @@ test('lists a route\'s pricing including blocked options', function () {
         ->getJson("/api/v1/routes/{$route->id}/pricing")
         ->assertSuccessful()
         ->assertJsonCount(2, 'data')
-        ->assertJsonFragment(['vehicle_option' => 'front_seat', 'price' => '12000.00', 'is_blocked' => false])
-        ->assertJsonFragment(['vehicle_option' => 'whole_vehicle', 'is_blocked' => true]);
+        ->assertJsonFragment([
+            'vehicle_option' => 'front_seat',
+            'price' => '12000.00',
+            'is_blocked' => false,
+            'max_per_booking' => config('booking.front_seat_max_per_booking'),
+        ])
+        ->assertJsonFragment([
+            'vehicle_option' => 'whole_vehicle',
+            'is_blocked' => true,
+            'max_per_booking' => config('booking.whole_vehicle_max_per_booking'),
+        ]);
 });
 
 test('lists a route\'s time slots with the pivot active flag', function () {