feat(maps): add MapLibre OpenFreeMap support (#1317)

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.

client/src/components/Map/MapViewAuto.tsx

@@ -1,21 +1,36 @@
+import { lazy, Suspense } from 'react'
 import { useSettingsStore } from '../../store/settingsStore'
 import { MapView } from './MapView'
-import { MapViewGL } from './MapViewGL'
+
+// MapLibre/Mapbox pull in a ~230 KB (gzip) GL engine. Lazy-load the GL renderer so
+// Leaflet-only installs never download it — it ships only once a GL provider is picked.
+const MapViewGL = lazy(() => import('./MapViewGL').then(m => ({ default: m.MapViewGL })))
 
 // Auto-selects the map renderer based on user settings. Keeps the existing
 // Leaflet MapView untouched so the Mapbox GL variant can mature iteratively
 // behind a toggle. Atlas is not affected — it imports Leaflet directly.
 //
 // Offline maps: only the Leaflet renderer supports full pre-download (raster
-// tiles via sync/tilePrefetcher.ts). Mapbox GL is best-effort offline — its
+// tiles via sync/tilePrefetcher.ts). GL maps are best-effort offline — their
 // vector tiles are cached opportunistically by the Service Worker as you view
-// them online (see the mapbox-tiles rule in vite.config.js), not prefetched.
+// them online (see the GL tile rules in vite.config.js), not prefetched.
 // eslint-disable-next-line @typescript-eslint/no-explicit-any
 export function MapViewAuto(props: any) {
   const provider = useSettingsStore(s => s.settings.map_provider)
   const token = useSettingsStore(s => s.settings.mapbox_access_token)
   // Fall back to Leaflet when Mapbox is selected but no token is set,
   // so trip planner never shows an empty map due to a missing token.
-  if (provider === 'mapbox-gl' && token) return <MapViewGL {...props} />
+  const glProvider = provider === 'maplibre-gl' ? 'maplibre-gl'
+    : provider === 'mapbox-gl' && token ? 'mapbox-gl'
+    : null
+  if (glProvider) {
+    // Render the previous Leaflet map as the fallback so there's no blank flash
+    // while the GL chunk loads on first use.
+    return (
+      <Suspense fallback={<MapView {...props} />}>
+        <MapViewGL {...props} glProvider={glProvider} />
+      </Suspense>
+    )
+  }
   return <MapView {...props} />
 }