feat: add drivable black luxury cars, Apache motorcycles and lane splitting

- Park black BMW, Lamborghini, Mazda and Nissan style cars in the factory
  yard; Mr Mohammadi now arrives in a Bugatti that becomes drivable once
  parked; the delivery truck is black.
- Add six Apache style motorcycles with a rider, lean and their own
  handling (BIKE spec, 130 km/h).
- Let the player take any traffic car; a garage module owns every
  drivable vehicle and resets them.
- Replace the 3.4 m circle test between vehicles with oriented boxes
  sized from each model, so contact only happens when bodies touch and
  bikes can filter between cars; traffic only brakes for its own lane.
- Add tests for box collisions, bike handling, traffic lane checks and
  taking traffic cars.

Co-Authored-By: Claude Opus 5.5 <noreply@anthropic.com>

src/constants/vehicles.js

@@ -0,0 +1,26 @@
+// Every vehicle in the factory yard is painted this gloss black.
+export const VEHICLE_BLACK = '#0c0d0f';
+
+// How close (metres, centre to centre) the player must stand to get on or in a vehicle.
+export const ENTER_DISTANCE = 4.5;
+
+// Above this speed (m/s) the player has to stop before getting off.
+export const EXIT_MAX_SPEED = 3;
+
+// Persian names shown in prompts. `bmw` is the family car parked beside the start point.
+export const VEHICLE_LABELS = {
+  bmw: 'بی‌ام‌و',
+  bugatti: 'بوگاتی',
+  lamborghini: 'لامبورگینی',
+  mazda: 'مزدا',
+  nissan: 'نیسان',
+  apache: 'موتور آپاچی',
+  traffic: 'ماشین',
+};
+
+// Brands parked in the staff bays, in bay order. Mr Mohammadi arrives in the Bugatti.
+export const STAFF_CAR_BRANDS = ['lamborghini', 'mazda', 'nissan'];
+export const MANAGER_CAR_BRAND = 'bugatti';
+
+// Apache motorcycles lined up in the yard.
+export const MOTORCYCLE_COUNT = 6;