fix: increase default widget preview dimensions for fullscreen view

Changes default widget preview dimensions from 128x128 to 960x640 so
table-based widgets like Docker containers aren't squished into a tiny
strip when viewed via the /widgets route in fullscreen mode.

Closes #6230

apps/nextjs/src/app/[locale]/widgets/[kind]/_content.tsx

@@ -37,8 +37,8 @@ export const WidgetPreviewPageContent = ({ kind, integrationData }: WidgetPrevie
   const currentDefinition = useMemo(() => widgetImports[kind].definition, [kind]);
   const [editMode, setEditMode] = useState(false);
   const [dimensions, setDimensions] = useState<Dimensions>({
-    width: 128,
-    height: 128,
+    width: 960,
+    height: 640,
   });
   const [state, setState] = useState<{
     options: Record<string, unknown>;