Fix edge cases and consistency issues

pixstrip-core/tests/preset_tests.rs

@@ -37,7 +37,7 @@ fn preset_serialization_roundtrip() {
 #[test]
 fn all_builtin_presets() {
     let presets = Preset::all_builtins();
-    assert_eq!(presets.len(), 8);
+    assert_eq!(presets.len(), 9);
     let names: Vec<&str> = presets.iter().map(|p| p.name.as_str()).collect();
     assert!(names.contains(&"Blog Photos"));
     assert!(names.contains(&"Social Media"));