Describe the bug
When running through nginx reverse proxy (which adds HTTPS and subdomains), CWA gives incorrect hint how to set up CWA KOReader plugin. In my case, it lists http://calibre.DOMAIN/kosync, while it should be https://calibre.DOMAIN.

When the /kosync is added to address, KOReader throws an error about some nonspecific server error. Without it, all works properly. Also, using the HTTP variant does not work, HTTPS has to be used.

To Reproduce
Steps to reproduce the behavior:

1. Start a docker environment with nginx reverse proxy which provides Letsencrypt companion and converts connections to HTTPS, add relevant info to /vhost (I can provide my configuration).
2. Start CWA with proper VIRTUAL_HOST and LETSENCRYPT_HOST parameters in Docker-compose file.
3. Go to KOSync page and have a look at the hints to configuration of plugin in KOReader.

Expected behavior
The /koreader part from address should be removed. If possible, HTTPS/HTTP detection could be added (or maybe could the plugin in KOReader detect automatically which one works?)

Screenshots

Configuration(please complete the following information):

• OS: Ubuntu 25.04, Docker environment with global reverse proxy
• Hardware: HP T640 (Ryzen R1505G, 20 GB RAM, 1 TB SSD)
• Version: 3.1.2, Docker container crocodilestick/calibre-web-automated:V3.1.2

Additional context
Nice work with CWA and Kobo related things otherwise!