fix: show watched icon only for individual watched videos instead of checking overall watched list

frontend/src/app/components/home/categories/video-list/video-list.component.html

@@ -9,7 +9,7 @@
         alt=""
       />
     </div>
-    @if (getWatchedVideos()) {
+    @if (watchedVideos.includes(video.id)) {
     <div class="watched">
       <img src="./assets/img/open-eye.svg" alt="" />
     </div>

frontend/src/app/components/home/categories/video-list/video-list.component.ts

@@ -29,16 +29,6 @@ export class VideoListComponent {
     return `${environment.baseUrl}/media/thumbnails/${id}/${fileName}_480p.jpg`;
   }
 
-  /**
-   * Filters and returns all watched videos.
-   * @returns An array of watched videos.
-   */
-  getWatchedVideos(): Video[] {
-    return this.videos.filter(
-      (video) => video.id !== undefined && this.watchedVideos.includes(video.id)
-    );
-  }
-
   /**
    * Set the current video based on the given videoId and emit the videoId.
    * @param videoId The id of the video to set as the current video.