chore: drop size from plugin window title (Figma title bar is not customizable; keep name only)

src/main.ts

@@ -10,5 +10,5 @@ export default function () {
     figma.ui.resize(width, height)
   })
 
-  showUI({ width: 320, height: 200, themeColors: true, title: 'AI assistant (MVP) — 320×200' })
+  showUI({ width: 320, height: 200, themeColors: true, title: 'AI assistant (MVP)' })
 }