Improve thumbnail loading reliability across the platform

Update video cards and video page to use a backup thumbnail URL from Bunny.net when the primary URL fails, enhancing robustness for video content display.

Replit-Commit-Author: Agent
Replit-Commit-Session-Id: d7424866-83d1-4486-a212-ac12b4c7becf
Replit-Commit-Checkpoint-Type: full_checkpoint
Replit-Commit-Screenshot-Url: https://storage.googleapis.com/screenshot-production-us-central1/8cc42625-c1f5-4e43-99bd-77f2c4dedee2/d7424866-83d1-4486-a212-ac12b4c7becf/d3pjSXi

server/bunny.ts

@@ -52,8 +52,9 @@ export class BunnyService {
   }
 
   private bunnyVideoToVideo(bunnyVideo: BunnyVideo): Video {
-    // Generate thumbnail URL from CDN (thumbnails are usually public)
+    // Generate multiple thumbnail URL options
     const thumbnailUrl = `https://${this.hostname}/${bunnyVideo.guid}/thumbnail.jpg`;
+    const backupThumbnailUrl = `https://iframe.mediadelivery.net/embed/${this.libraryId}/${bunnyVideo.guid}/thumbnail.jpg`;
 
     // Generate signed HLS URL for private video access
     const hlsUrl = this.generateSignedUrl(bunnyVideo.guid);