Use 1280x800 for OpenAI CUA template viewport

Switch the OpenAI template browser viewport to 1280x800, the resolution
OpenAI recommends for the computer-use tool in their current docs.

Co-Authored-By: Claude Opus 4.7 <noreply@anthropic.com>

Author: dprevoznik

pkg/templates/typescript/openai-computer-use/index.ts

@@ -28,7 +28,7 @@ app.action<CuaInput, CuaOutput>(
 
     const browser = await kernel.browsers.create({
       invocation_id: ctx.invocation_id,
-      viewport: { width: 1920, height: 1080 },
+      viewport: { width: 1280, height: 800 },
     });
     console.log('Kernel browser live view url:', browser.browser_live_view_url);