feat(shorts): 11 animated bg motifs (grid/dots/waves/stars/zigzag/brackets) + per-script seed shuffle

src/remotion/index.tsx

@@ -14,7 +14,7 @@ const Shorts: React.FC = () => {
       fps={30}
       width={1080}
       height={1920}
-      defaultProps={{ segments: DEFAULT_SEGMENTS }}
+      defaultProps={{ segments: DEFAULT_SEGMENTS, seed: 0 }}
       calculateMetadata={({ props }) => {
         const segs = props.segments?.length ? props.segments : DEFAULT_SEGMENTS;
         return { durationInFrames: useTotalDuration(segs) };