The managed runtime for the Java language server was a Temurin JRE, which lacks jdk.jdi. java-debug runs inside the jdtls JVM, so Debug failed with NoClassDefFoundError com/sun/jdi/VMDisconnectedException and "debug adapter did not answer initialize in time" while Run worked. Provision a full JDK instead and replace an already-downloaded JRE runtime (Temurin's JRE lists jdk.jdi in release MODULES although the image omits it, so suitability checks IMAGE_TYPE, javac and the modules); auto-picked installed runtimes must also carry jdk.compiler, jdk.jdi and jdk.unsupported, and a user-chosen language-server JDK without them gets a clear warning. Fixes#765.
