Fix S3 keys/paths for user avatars

Also fixes the avatars controller to work with all back-ends

app/controllers/avatars_controller.rb

@@ -4,17 +4,23 @@ class AvatarsController < ApplicationController
       http_status :not_found and return unless user.avatar.attached?
 
       sha256_hash = params[:hash]
-      format = params[:format].to_sym || :png
-      size = params[:size]&.to_sym || :large
+      format = params[:format]&.to_sym || :png
+      size = params[:size]&.to_sym || :original
 
-      unless user.avatar_filename == "#{sha256_hash}.#{format}"
+      unless user.avatar.filename.to_s == "#{sha256_hash}.#{format}"
         http_status :not_found and return
       end
 
-      send_file user.avatar.service.path_for(user.avatar.key),
-        disposition: "inline", type: "image/#{format}"
+      blob = if size == :original
+               user.avatar.blob
+             else
+               user.avatar_variant(size: size)&.blob
+             end
+
+      data = blob.download
+      send_data data, type: "image/#{format}", disposition: "inline"
     else
-      http_status :not_found and return
+      http_status :not_found
     end
   end
 end