Play feature under the menu; add mpv path; simplify VLC launch

Root causes found this session (all player-side, disc is valid -- bd_info
validates it and mpv plays the ISO's feature directly):

- Plain 'vlc <iso>' can't run ANY BD-J: system Java is 26, and libbluray's BD-J
  needs a JVM where System.setSecurityManager() works (<=21). run-vlc.sh pins
  mise Temurin 8, which is why it gets a menu at all.
- The BD-J VFS-cache 'error creating /tmp/libbluray-bdj-cache' flood is
  libbluray's SecurityManager.canWrite() denying the cache root while an Xlet
  context is active. Fixed by pointing TMPDIR at LIBBLURAY_CACHE_ROOT (buda
  root), which canWrite() allows unconditionally.
- Menu->playback failed with 'blurayReleaseVout: subpicture channel exists':
  VLC botches the background->playlist transition for an idle BD-J menu. Now the
  Xlet starts the feature immediately and draws the menu on top, so VLC stays in
  normal playing mode; MAIN FEATURE just hides the menu, any key brings it back,
  and the feature loops.

Also: drop the redundant tools/vlc-plugins swap (system VLC already ships the
bluray plugin), and add scripts/run-mpv.sh to play the feature with no BD-J/JVM
at all. Vendored the SDK helloworld sample for reference.

Co-Authored-By: Claude Opus 4.8 <noreply@anthropic.com>

src/org/homebrew/AdjustmentsMenu.java

@@ -7,8 +7,15 @@ import java.awt.FontMetrics;
 import java.awt.Graphics;
 import java.awt.event.KeyEvent;
 import java.awt.event.KeyListener;
+import javax.media.ControllerEvent;
+import javax.media.ControllerListener;
+import javax.media.EndOfMediaEvent;
+import javax.media.Manager;
+import javax.media.MediaLocator;
+import javax.media.Player;
+import javax.media.Time;
 
-public class AdjustmentsMenu extends Container implements KeyListener {
+public class AdjustmentsMenu extends Container implements KeyListener, ControllerListener {
     private static final String[] MAIN_ITEMS = {
         "MAIN FEATURE",
         "BONUS: WAITING ROOM OUTTAKES",
@@ -30,6 +37,8 @@ public class AdjustmentsMenu extends Container implements KeyListener {
     private boolean hidden;
     private int codeProgress;
     private String status = "BD-J scaffold loaded";
+    private Player featurePlayer;
+    private boolean menuShown = true;
 
     public AdjustmentsMenu() {
         setFocusable(true);
@@ -111,7 +120,11 @@ public class AdjustmentsMenu extends Container implements KeyListener {
             selected = 0;
             status = "Returned to approved materials";
         } else if ("MAIN FEATURE".equals(item)) {
-            status = "Main feature is playlist 00000";
+            // The feature is already playing behind the menu; just hide the
+            // menu to reveal it. Press the menu key (or ENTER) to bring it back.
+            status = "Playing main feature -- press ENTER for menu";
+            setMenuVisible(false);
+            return;
         } else if ("SETTINGS".equals(item)) {
             status = "Settings stub selected";
         } else {
@@ -121,6 +134,47 @@ public class AdjustmentsMenu extends Container implements KeyListener {
         repaint();
     }
 
+    // Called once by the Xlet at startup. Start the feature playing straight
+    // away and leave it running for the whole session. This keeps VLC in normal
+    // "playing" mode with a live playlist behind the menu, so selecting an item
+    // never triggers the background->playlist transition that VLC botches
+    // ("blurayReleaseVout: subpicture channel exists", no video). The menu is
+    // just drawn on top and toggled with setMenuVisible().
+    public void startPlayback() {
+        if (featurePlayer != null) {
+            return;
+        }
+        try {
+            // libbluray's "bd" protocol; PLAYLIST:00000 -> BDMV/PLAYLIST/00000.mpls.
+            featurePlayer = Manager.createPlayer(new MediaLocator("bd://PLAYLIST:00000"));
+            featurePlayer.addControllerListener(this);
+            featurePlayer.start();
+        } catch (Exception e) {
+            featurePlayer = null;
+            status = "Playback failed: " + e.getMessage();
+        }
+        repaint();
+    }
+
+    // Toggle only this menu Container, not the whole HScene, so the scene (and
+    // its key listener) stays alive while the video shows underneath.
+    private void setMenuVisible(boolean visible) {
+        menuShown = visible;
+        setVisible(visible);
+        if (visible) {
+            requestFocus();
+        }
+        repaint();
+    }
+
+    public void controllerUpdate(ControllerEvent event) {
+        // Loop the feature so there is always a live playlist behind the menu.
+        if (event instanceof EndOfMediaEvent && featurePlayer != null) {
+            featurePlayer.setMediaTime(new Time(0));
+            featurePlayer.start();
+        }
+    }
+
     private void unlockHidden() {
         hidden = true;
         selected = 0;
@@ -131,6 +185,14 @@ public class AdjustmentsMenu extends Container implements KeyListener {
 
     public void keyPressed(KeyEvent e) {
         int code = e.getKeyCode();
+
+        // When the menu is hidden (feature playing full screen), any key brings
+        // the menu back over the still-running video.
+        if (!menuShown) {
+            setMenuVisible(true);
+            return;
+        }
+
         String[] items = hidden ? HIDDEN_ITEMS : MAIN_ITEMS;
 
         if (code == KeyEvent.VK_UP) {

src/org/homebrew/MyXlet.java

@@ -29,6 +29,9 @@ public class MyXlet extends Thread implements Xlet {
         scene.setVisible(true);
         menu.requestFocus();
         scene.requestFocus();
+        // Start the feature immediately so VLC always has a live playlist behind
+        // the menu (avoids the background->playlist transition it botches).
+        menu.startPlayback();
         start();
     }