Remember how tall the user made the info panel

Kept as a share of the tree/info column, so it survives new tabs, a resized
window and the next session.

Co-Authored-By: Claude Opus 5 <noreply@anthropic.com>

ts3-client/swing/src/main/java/com/ts3client/ui/MainFrame.java

@@ -723,6 +723,7 @@ public final class MainFrame extends JFrame implements ServerTabPane.Listener {
     private void shutdown() {
         if (!shuttingDown.compareAndSet(false, true)) return;
         if (statusTimer != null) statusTimer.stop();
+        settings.save(); // keeps the layout the user left behind (info panel height, …)
         try {
             Runtime.getRuntime().removeShutdownHook(shutdownHook);
         } catch (IllegalStateException ignored) {