Fix Nginx 413 Request Entity Too Large

POSTing a file larger than ~1 MB returns `413 Request Entity Too Large`.

Nginx defaults `client_max_body_size` to 1 MB. Any larger request body is rejected before reaching the upstream.

Raise the limit in the right scope

http {
  client_max_body_size 50m;   # global default
}

server {
  client_max_body_size 200m;  # override for this vhost
}

Reload Nginx

sudo nginx -t && sudo systemctl reload nginx