FreshRSS with built-in extensions

This is a Docker image built from the official FreshRSS base image, which includes built-in extensions:

• Image Proxy (to add a HTTP prefix URL for all images in a feed)
• Reading Time (to add estimated reading time for a feed item)
• GReader Redate (use published time rather than the fetching time)
• TranslateTitlesCN (to translate titles into Chinese)

Why we need this

FreshRSS extensions need to be available on this default path in container: /var/www/FreshRSS/extensions. But fly.io doesn’t support having same mount for mulitple directories, or having multiple mounts. If we try mount the parent path /var/www/FreshRSS, it'll led to kernel panic. So I want it works on fly.io when I'm only able to mount the data path with /var/www/FreshRSS/data. See fly.toml file.