Implement the Fan-In Fan-Out concurrency pattern for efficient processing of NSFW image detection. The process involves two distinct worker types:
-> Downloader Workers (Fan-Out):
Gather and download files.
After downloading, place the file references into a shared queue.
-> Scanner Workers (Fan-In):
Extract file references from the shared queue.
Run the NSFW scanner on each file.
Determine if the file is NSFW or safe.