Refactor desktop sample build configuration to use standard JVM target

- Renamed the JVM target from `"desktop"` to the default `jvm()`.
- Renamed the source set from `desktopMain` to `jvmMain` to match the default Kotlin Multiplatform naming convention.
- Added the `compose.desktop.currentOs` dependency to `jvmMain`.

Author: softartdev

sample/desktop/build.gradle.kts

@@ -9,14 +9,15 @@ plugins {
 
 kotlin {
     jvmToolchain(libs.versions.jdk.get().toInt())
-    jvm("desktop") {
+    jvm {
         compilerOptions.jvmTarget = JvmTarget.fromTarget(libs.versions.jdk.get())
     }
     sourceSets {
-        val desktopMain by getting {
+        val jvmMain by getting {
             dependencies {
                 implementation(projects.sample.shared)
                 implementation(libs.compose.desktop)
+                implementation(compose.desktop.currentOs)
             }
         }
     }