fix(test): use REDIS_ADDR environment variable in test mocks to match CI service hostname

cmd/api/handlers_test.go

@@ -44,8 +44,15 @@ func flushRedisForTest(t *testing.T, client *redis.Client) {
 }
 
 func newMockHandlerContext() *HandlerContext {
+	// Read Redis address from environment, default to localhost:6379
+	redisAddr := os.Getenv("REDIS_ADDR")
+	if redisAddr == "" {
+		redisAddr = "localhost:6379"
+	}
 	redisClient := redis.NewClient(&redis.Options{
-		Addr: "localhost:6379",
+		Addr:     redisAddr,
+		Password: "",
+		DB:       0,
 	})
 
 	// Create an empty routing graph