fix: use of auto with kotlin jvm target

Signed-off-by: Sam Gammon <sam@elide.dev>

Author: sgammon

packages/builder/src/main/kotlin/elide/tooling/jvm/JvmBuildConfigurator.kt

@@ -638,7 +638,10 @@ internal class JvmBuildConfigurator : BuildConfigurator {
       }.map { it.path.toFile() }
 
       incrementalCompilation = state.manifest.kotlin?.features?.incremental != false
-      jvmTarget = effectiveJvmTarget.argValue
+      jvmTarget = when (val tgt = effectiveJvmTarget.argValue) {
+        "auto" -> ElidePackageManifest.JvmTarget.DEFAULT.argValue
+        else -> tgt
+      }
 
       // handle built-in plugins
       if (state.manifest.kotlin?.features?.enableDefaultPlugins != false) {