Add main class configuration for application plugin

Configured the 'application' plugin with the main class to ensure the application starts with the correct entry point. This change is necessary for proper execution of the program when deploying or running from the build system.

build.gradle.kts

@@ -75,6 +75,10 @@ kotlin {
     }
 }
 
+application {
+    mainClass.set("nl.astraeus.vst.string.MainKt")
+}
+
 /* Hardcoded deploy configuration */
 
 val deployDirectory = "vst-string.midi-vst.com"