Fixed the Map gauge's Dark and Light styles showing an "API key required" watermark.

Carto, the provider behind the Map gauge's Dark and Light basemap styles, changed their terms and started requiring an API key on tiles that used to be fully open — which broke both styles in production, showing a watermark instead of the actual map.

Fixed by routing those tiles through our own server instead of fetching them directly from the browser. Streets and Topo styles were never affected.