frontend: wait on SplatMesh.initialized instead of an unused instance's onLoad (Sonar S1848)

frontend/libs/components/pagescene/src/lib/engine/scene.ts

@@ -1079,15 +1079,10 @@ class Scene {
       }
       throw error;
     }
-    return new Promise((resolve) => {
-      new SplatMesh({
-        fileBytes: buffer,
-        onLoad: (mesh) => {
-          resolve(mesh);
-          onComplete();
-        },
-      });
-    });
+    const mesh = new SplatMesh({ fileBytes: buffer });
+    await mesh.initialized;
+    onComplete();
+    return mesh;
   }
 
   /**

frontend/libs/components/viewer-3d/src/lib/viewer-3d.tsx

@@ -408,9 +408,8 @@ export function Viewer3D({
 
     if (SPLAT_EXTENSIONS.includes(urlExtension)) {
       console.log(`[Viewer3D] splat format detected (.${urlExtension})`);
-      new SplatMesh({
-        url: modelUrl,
-        onLoad: (mesh) => {
+      void new SplatMesh({ url: modelUrl }).initialized
+        .then((mesh) => {
           if (cancelled) {
             mesh.dispose();
             return;
@@ -434,8 +433,10 @@ export function Viewer3D({
           }
 
           console.log("Splat loaded");
-        },
-      });
+        })
+        .catch((error) =>
+          console.error("[Viewer3D] splat load failed:", error),
+        );
     } else if (!GLTF_EXTENSIONS.includes(urlExtension)) {
       // Known non-glTF model format with no loader wired here (obj, fbx,
       // pmx, …). Show the fallback shape rather than spamming a parse error.