Import missing artist portraits from uploaded album folders

deploy/nginx/default.conf.template

@@ -24,7 +24,8 @@ server {
     real_ip_recursive on;
 
     root /usr/share/nginx/html;
-    client_max_body_size 16m;
+    # Two images (album cover + artist portrait), each up to 8 MiB before base64.
+    client_max_body_size 32m;
 
     include /etc/nginx/snippets/security-headers.conf;