feat: expose hotel cost unit and iso country code via the api

The Teamer app groups hotels by cost unit and renders a flag per
destination, and cannot derive either from what /api/hotels returns
today.

costUnit is the raw kostenstelle and stays a string: only 281 of 1931
hotels carry one and some hold a space-separated list such as "84 85".

countryCode goes through CountryCodeMapper, whose table is part of the
API contract: BusPro's land column mixes ISO-2, ISO-3 and European
vehicle registration codes for the same country, and a wrong entry
mislabels a destination's flag silently. An unmappable token is null and
warns on the bpn channel, never a guess. country itself is untouched --
it remains the join key into /api/countries[].token.

Co-Authored-By: Claude Opus 5 <[email protected]>

tests/BusProNet/DataLoader/HotelDataLoaderTest.php

@@ -3,9 +3,11 @@
 namespace App\Tests\BusProNet\DataLoader;
 
 use App\BusProNet\Model\Hotel;
+use App\BusProNet\Utility\CountryCodeMapper;
 use App\BusProNet\XmlLoader\HotelLoader;
 use League\Flysystem\FilesystemOperator;
 use PHPUnit\Framework\TestCase;
+use Psr\Log\NullLogger;
 use Symfony\Component\Cache\Adapter\ArrayAdapter;
 use Symfony\Component\Cache\Adapter\TagAwareAdapter;
 
@@ -34,7 +36,7 @@ class HotelDataLoaderTest extends TestCase
             ->willReturn($xmlContent);
 
         $cache = new TagAwareAdapter(new ArrayAdapter());
-        $loader = new HotelLoader($cache, $filesystem);
+        $loader = new HotelLoader(new CountryCodeMapper(new NullLogger()), $cache, $filesystem);
 
         $hotels = $loader->loadAll();
 
@@ -50,5 +52,7 @@ class HotelDataLoaderTest extends TestCase
         $this->assertEquals('F', $hotel->country);
         $this->assertEquals('Rue des Lacs', $hotel->street);
         $this->assertEquals('', $hotel->phone);
+        $this->assertEquals('fr', $hotel->countryCode);
+        $this->assertNull($hotel->costUnit);
     }
 }