rename backend to core

core/internal/server/brightness/manager_test.go

@@ -0,0 +1,11 @@
+package brightness
+
+import (
+	"testing"
+)
+
+// Manager tests can be added here as needed
+func TestManager_Placeholder(t *testing.T) {
+	// Placeholder test to keep the test file valid
+	t.Skip("No tests implemented yet")
+}