fix(api): add rate limiting, file size validation, and timeout handling

- Add Content-Length header check for early file size validation on audio upload
- Add rate limiting (60 req/min) to public watch endpoint
- Add 10-second timeout with AbortController for YouTube and Vimeo oEmbed requests
- Add automatic rate limit cleanup interval for self-hosted servers
- Fix null check for comment.replies in video page content
- Add checkWorkspaceAccess helper for workspace authorization

components/video-page-content.tsx

@@ -2224,7 +2224,7 @@ export function VideoPageContent({ mode, videoId, projectId: propProjectId }: Vi
                         )}
                       </div>
 
-                      {comment.replies.length > 0 && (
+                      {comment.replies && comment.replies.length > 0 && (
                         <div className="mt-3 pl-3 border-l-2 space-y-2">
                           {comment.replies.map((reply) => {
                             const replyAuthor =