fix(v2): order artwork images before videos, narrow filter with type guard

Sort library media so image entries precede video entries (stable sort
keeps original order within each group), and use a type-predicate filter
so the result stays typed as RomArtworkEntry[].

Generated-By: PostHog Code
Task-Id: fad7faa2-a17e-4583-a816-1b9915ba138f

Author: gantoine

frontend/src/v2/utils/romArtwork.ts

@@ -134,7 +134,9 @@ export function resolveRomArtwork(rom: DetailedRom): RomArtworkEntry[] {
         isVideo,
       };
     })
-    .filter((entry) => entry !== null);
+    .filter((entry): entry is NonNullable<typeof entry> => entry !== null)
+    // Images before videos; sort is stable so original order holds within each group.
+    .sort((a, b) => Number(a.isVideo) - Number(b.isVideo));
 
   for (const def of artworkDefs) {
     if (!def.url || seen.has(def.url)) continue;