Add side-by-side comparison via new Copilot menu entry

- Add 'Compare Chat View Rendering Alternatives' Copilot menu entry
- Opens both rendering alternatives in one dialog, side by side, for visual comparison

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

Author: travkin79

com.microsoft.copilot.eclipse.ui.test/META-INF/MANIFEST.MF

@@ -29,4 +29,5 @@ Require-Bundle: org.mockito.mockito-core;bundle-version="5.14.2",
  org.eclipse.e4.core.services;bundle-version="2.4.200",
  org.osgi.service.event,
  com.google.gson,
- com.microsoft.copilot.eclipse.terminal.api;bundle-version="0.20.0"
+ com.microsoft.copilot.eclipse.terminal.api;bundle-version="0.20.0",
+ org.eclipse.e4.ui.css.swt.theme;bundle-version="0.14.500"

com.microsoft.copilot.eclipse.ui.test/plugin.xml

@@ -23,4 +23,29 @@
             name="Editor for Refactor Rename Tests"/>
    </extension>
 
+   <extension
+         point="org.eclipse.ui.commands">
+      <command
+            id="copilot.test.compareRenderers"
+            name="Compare Chat View Rendering Alternatives"/>
+   </extension>
+
+   <extension
+         point="org.eclipse.ui.handlers">
+      <handler
+            class="com.microsoft.copilot.eclipse.ui.chat.ConversationRendererVisualDemoSideBySide"
+            commandId="copilot.test.compareRenderers"/>
+   </extension>
+
+   <extension
+         point="org.eclipse.ui.menus">
+      <menuContribution
+            locationURI="menu:com.microsoft.copilot.eclipse.ui.menuBar?after=additions">
+         <command
+               commandId="copilot.test.compareRenderers"
+               label="Compare Chat View Rendering Alternatives"
+               style="push"/>
+      </menuContribution>
+   </extension>
+
 </plugin>