v3: allow users to edit dump thumbnail, fixed some linter errors in the frontend

src/components/MediaPlayer.tsx

@@ -127,6 +127,7 @@ interface MediaPlayerProps {
   src: string;
   kind: "audio" | "video";
   mime?: string;
+  poster?: string;
   autoplay?: boolean;
   onPlayStateChange?: (playing: boolean) => void;
   onTimeUpdate?: (time: number, duration: number) => void;
@@ -139,6 +140,7 @@ export function MediaPlayer(
     src,
     kind,
     mime,
+    poster,
     autoplay,
     onPlayStateChange,
     onTimeUpdate,
@@ -422,6 +424,7 @@ export function MediaPlayer(
         <video
           ref={mediaRef as React.RefObject<HTMLVideoElement>}
           src={src}
+          poster={poster}
           preload="metadata"
           className="video-player-video"
           onClick={toggle}