Update knob component defaults and clean up unused code

Adjusted the default value, minValue, and step for the volume knob to improve precision. Removed unused `KnobBackgroundCls` and cleaned up unnecessary whitespace for better readability and maintainability.

test-app/src/jsMain/kotlin/nl/astraeus/vst/ui/view/MainView.kt

@@ -137,11 +137,11 @@ class MainView : Komponent() {
         div(ControlsCss.name) {
           include(
             ExpKnobComponent(
-              value = 0.0,
+              value = 0.001,
               label = "Volume",
-              minValue = 0.0,
+              minValue = 0.001,
               maxValue = 1.0,
-              step = 5.0 / 127.0,
+              step = 10.0 / 127.0,
               width = 100,
               height = 120,
             ) { value ->