Fix UserPreferenceService.unbindChatView() thread safety

Wrap the chatViewSideEffect disposal in ensureRealm() to guarantee it
runs on the correct data binding Realm thread, preventing potential
InvalidThreadAccessException when unbinding from a non-UI thread.

Co-authored-by: Copilot <223556219+Copilot@users.noreply.github.com>

Author: travkin79

com.microsoft.copilot.eclipse.ui/src/com/microsoft/copilot/eclipse/ui/chat/services/UserPreferenceService.java

@@ -503,10 +503,12 @@ public void bindChatView(ChatView chatView) {
    * Unbind the currently bound chat view if any.
    */
   public void unbindChatView() {
-    if (chatViewSideEffect != null) {
-      chatViewSideEffect.dispose();
-      chatViewSideEffect = null;
-    }
+    ensureRealm(() -> {
+      if (chatViewSideEffect != null) {
+        chatViewSideEffect.dispose();
+        chatViewSideEffect = null;
+      }
+    });
   }
 
   /**