feat(editor): Change Code Editor to show diffs in source control panel and during messaging.

Add merge view and minimap extensions to CodeMirror for enhanced code
editing capabilities. Increase Express JSON and URL-encoded payload
limits from default (100kb) to 50mb to support larger file operations
and git diffs.

src/App.jsx

@@ -184,11 +184,7 @@ function AppContent() {
 
               if (!isSessionActive) {
                 // Session is not active - safe to reload messages
-                console.log('🔄 External CLI update detected for current session:', changedSessionId);
                 setExternalMessageUpdate(prev => prev + 1);
-              } else {
-                // Session is active - skip reload to avoid interrupting user
-                console.log('⏸️ External update paused - session is active:', changedSessionId);
               }
             }
           }