fix(imgproxy): fallback to smart gravity (sm) instead of face detection (fv)

- 'fv' requires ML modules not present in standard imgproxy image
- 'sm' is robust and supported everywhere
- Fixes broken images on staging using Next.js Image loader

lib/imgproxy-loader.ts

@@ -28,6 +28,6 @@ export default function imgproxyLoader({
   return getImgproxyUrl(src, {
     width,
     resizing_type: 'fit',
-    gravity: 'fv', // Use face-aware focusing (face detection)
+    gravity: 'sm', // Use smart gravity (content-aware) instead of face detection (requires ML)
   });
 }