maps: wikimedia tiles not loading anymore

The Wikimedia Foundation has blocked requests with the architrave.eu referrer (which is in line with their policy). Therefore, the wikimedia layer on all three maps aren't rendering anymore. Its most obvious here: https://architrave.eu/itinerary.html?lang=fr#?tab-id=EuropeMap

I could just replace the link to the tile layer with a suitable alternative. On the other hand, since the required map region isn't huge, I could also reference tiles on our web server. We'd need to deposit a single tiles file (~ 22G) on a web server that supports http range requests. @sfunk, would that be feasible without a ton of work, maybe at the same spot where the /paris-project/ stuff is hosted? If not, no problem, I we'll integrate a third-party tile server.

Thanks!