feat: implement rewards module with referral/coupon systems, update tariff seeding, and add trip distance service for improved billing accuracy.

backend/src/modules/auth/auth.controller.ts

@@ -35,9 +35,11 @@ export class AuthController {
     @Headers('x-device-id') deviceId: string,
     @Body('phone') phone: string,
     @Body('code') code: string,
+    // كود دعوة اختياري — يُسجَّل للمستخدم الجديد وحده (المجموعة L).
+    @Body('referral_code') referralCode?: string,
   ) {
     if (!tenantId) throw new UnauthorizedException('Tenant ID (x-tenant-id) is required');
-    return this.authService.verifyOtp(tenantId, phone, code, deviceId);
+    return this.authService.verifyOtp(tenantId, phone, code, deviceId, referralCode);
   }
 
   @Post('refresh')