feat(llm): add new models for xAI and Google providers

Add 'grok-3-beta' to xAI provider and 'gemini-2.5-flash-preview-04-17' to Google provider. Also, ensure file saving when content is updated in WorkbenchStore and update streaming indicator styling in chat messages.

app/components/chat/Messages.client.tsx

@@ -102,7 +102,7 @@ export const Messages = forwardRef<HTMLDivElement, MessagesProps>(
             })
           : null}
         {isStreaming && (
-          <div className="text-center w-full text-bolt-elements-textSecondary i-svg-spinners:3-dots-fade text-4xl mt-4"></div>
+          <div className="text-center w-full  text-bolt-elements-item-contentAccent i-svg-spinners:3-dots-fade text-4xl mt-4"></div>
         )}
       </div>
     );