Update to version 2.1.1-SNAPSHOT and improve KeyboardComponent note handling

Bumped project version to 2.1.1-SNAPSHOT in `build.gradle.kts`. Enhanced `KeyboardComponent` logic to visually indicate pressed keys with new CSS classes for both white and black keys. Added `requestUpdate` calls to ensure UI updates on note changes. Simplified JVM target configuration in build script.

build.gradle.kts

@@ -10,7 +10,7 @@ plugins {
 }
 
 group = "nl.astraeus"
-version = "2.1.0"
+version = "2.1.1-SNAPSHOT"
 
 repositories {
     mavenCentral()
@@ -37,9 +37,7 @@ kotlin {
             }
         }
     }
-    jvm {
-        withJava()
-    }
+    jvm {}
 
     sourceSets {
         val commonMain by getting {