On a GL map (Mapbox Standard) the basemap labels fell back to the browser/OS locale, so place and country names showed stacked in several scripts (e.g. 'India / भारत / India') regardless of the chosen language. Pin Mapbox Standard's basemap label language to the user's UI language via the basemap 'language' config property, mapping the few TREK codes that differ (br->pt, gr->el, zh/zhTw->zh-Hans/zh-Hant). Applies to both the trip map and the journey map; classic and MapLibre styles are left unchanged.
Adds MapLibre GL with OpenFreeMap as a tokenless third map provider
alongside Leaflet and Mapbox: a provider abstraction with style presets,
CSP + service-worker entries for tiles.openfreemap.org, and the
map_provider allow-list entry. Mapbox-only APIs stay gated behind the
mapbox provider, and existing Mapbox/Leaflet users are unaffected.
Maintainer review follow-ups folded in: the new map-settings strings are
translated across all locales; the GL engine is lazy-loaded so
Leaflet-only installs don't download it; MapLibre gets its own
maplibre_style slot so switching providers no longer overwrites a custom
Mapbox style; and the MapLibre render path plus the OpenFreeMap
style-guards are covered by tests.
Maurice