JavaAPI: add Thread.setDaemon/isDaemon (the real missing-wrapper cause)

The interactive demo's undefined virtual_java_lang_Thread_setDaemon was not a
reachability/devirtualization quirk: the JavaAPI java.lang.Thread simply had no
setDaemon method, so when an app reaches the port's capturePhoto path (the demo's
camera button does; the suite never does) the translator has no body to emit ->
undefined symbol. Any minimal app using camera/the async port paths would hit
this. Add setDaemon(boolean)/isDaemon() (store the flag) -- verified locally that
java_lang_Thread.c now emits both the body and the virtual wrapper, and
LinuxImplementation.c now includes the header. Drop the demo-launcher force.

Co-Authored-By: Claude Opus 4.8 (1M context) <noreply@anthropic.com>

Author: shai-almog

vm/JavaAPI/src/java/lang/Thread.java

@@ -54,6 +54,7 @@ public class Thread implements java.lang.Runnable{
     private String name;
     private int priority = NORM_PRIORITY;
     private long nativeThreadId;
+    private boolean daemon;
     private static int activeThreads = 0;
 
     /**
@@ -97,6 +98,21 @@ public static int activeCount() {
         return activeThreads;
     }
 
+    /**
+     * Marks this thread as either a daemon thread or a user thread. Stored for
+     * API compatibility; the concurrent GC tracks lightweight threads regardless.
+     */
+    public final void setDaemon(boolean on) {
+        this.daemon = on;
+    }
+
+    /**
+     * Tests whether this thread is a daemon thread.
+     */
+    public final boolean isDaemon() {
+        return daemon;
+    }
+
     /**
      * Returns a reference to the currently executing Thread object.
      */

vm/tests/src/test/java/com/codename1/tools/translator/CleanTargetLinuxIntegrationTest.java

@@ -108,12 +108,6 @@ static String linuxDemoLauncherSource() {
                 "  static Form home;\n" +
                 "  public static void main(String[] args) {\n" +
                 "    Display.init(null);\n" +
-                // The port creates daemon worker threads via Thread.setDaemon -- a
-                // *virtual* wrapper this minimal app would not otherwise reach. Force
-                // it through a receiver whose runtime type the translator cannot pin
-                // down (currentThread()), so it cannot devirtualize to a direct call
-                // and must emit the virtual wrapper. The branch never runs.
-                "    if (args != null && args.length < 0) { Thread.currentThread().setDaemon(true); }\n" +
                 "    Display.getInstance().callSerially(new Runnable(){ public void run(){ build(); } });\n" +
                 "    LinuxImplementation.runMainEventLoop();\n" +
                 "  }\n" +