Remove hardcoded Redis URL from tests

- Read REDIS_URL from environment
- Skip tests if not set

tests/RedisCacheTest.php

@@ -17,14 +17,22 @@ use PHPUnit\Framework\TestCase;
 
 /**
  * Tests for Redis-backed caching.
+ * 
+ * Requires REDIS_URL environment variable. Tests will skip if not set.
  */
 class RedisCacheTest extends TestCase
 {
     private CacheInterface $redisCache;
-    private string $redisUrl = 'REDIS_URL_FROM_ENV';
+    private ?string $redisUrl = null;
 
     protected function setUp(): void
     {
+        $this->redisUrl = getenv('REDIS_URL') ?: null;
+        
+        if ($this->redisUrl === null) {
+            $this->markTestSkipped('REDIS_URL not set, skipping Redis tests');
+        }
+
         $this->redisCache = RedisCache::fromUrl($this->redisUrl, 'test_ctx:');
     }