Use branded StreamHoard placeholder for missing movie/show artwork

AlbumArt was music-only until now; movies and series grids/detail views
still showed a broken-image icon when poster_url/backdrop_url was empty.
Reused the same component (movies library grid, series grid + resume
strip, show detail backdrop, movie detail modal backdrop) instead of
duplicating the placeholder logic.

frontend/src/components/MovieCard.jsx

@@ -1,4 +1,5 @@
 import { Play } from "lucide-react";
+import AlbumArt from "./AlbumArt";
 
 export const MovieCard = ({ movie, onClick, progress }) => {
   const pct = progress?.duration_seconds
@@ -10,13 +11,7 @@ export const MovieCard = ({ movie, onClick, progress }) => {
       className="group relative shrink-0 w-[180px] md:w-[220px] aspect-[2/3] overflow-hidden bg-[#0F0F0F] transition-all duration-300 hover:scale-105 hover:z-10 focus:outline-none focus:ring-2 focus:ring-[#D9381E]"
       data-testid={`movie-card-${movie.id}`}
     >
-      <img
-        src={movie.poster_url || movie.backdrop_url}
-        alt={movie.title}
-        loading="lazy"
-        className="w-full h-full object-cover"
-        onError={(e) => { e.currentTarget.style.opacity = 0.3; }}
-      />
+      <AlbumArt url={movie.poster_url || movie.backdrop_url} loading="lazy" />
       <div className="absolute inset-0 bg-gradient-to-t from-black via-black/30 to-transparent opacity-90 md:opacity-0 group-hover:opacity-100 transition-opacity duration-300" />
       <div className="absolute inset-x-0 bottom-0 p-4 translate-y-2 md:translate-y-0 md:opacity-0 group-hover:opacity-100 group-hover:translate-y-0 transition-all duration-300">
         <h3 className="font-display text-lg font-bold tracking-tight text-white leading-none line-clamp-2">