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/glProviders.ts

@@ -0,0 +1,68 @@
+export type GlMapProvider = 'mapbox-gl' | 'maplibre-gl'
+
+export interface GlStylePreset {
+  name: string
+  url: string
+  tags?: string[]
+}
+
+export const MAPBOX_DEFAULT_STYLE = 'mapbox://styles/mapbox/standard'
+export const OPENFREEMAP_DEFAULT_STYLE = 'https://tiles.openfreemap.org/styles/liberty'
+
+export const MAPBOX_STYLE_PRESETS: GlStylePreset[] = [
+  { name: 'Mapbox Standard', url: MAPBOX_DEFAULT_STYLE, tags: ['3D', 'Apple-like'] },
+  { name: 'Standard Satellite', url: 'mapbox://styles/mapbox/standard-satellite', tags: ['3D', 'Satellite'] },
+  { name: 'Streets', url: 'mapbox://styles/mapbox/streets-v12', tags: ['3D', 'Classic'] },
+  { name: 'Outdoors', url: 'mapbox://styles/mapbox/outdoors-v12', tags: ['3D', 'Terrain'] },
+  { name: 'Light', url: 'mapbox://styles/mapbox/light-v11', tags: ['3D', 'Minimal'] },
+  { name: 'Dark', url: 'mapbox://styles/mapbox/dark-v11', tags: ['3D', 'Dark'] },
+  { name: 'Satellite', url: 'mapbox://styles/mapbox/satellite-v9', tags: ['3D', 'Satellite'] },
+  { name: 'Satellite Streets', url: 'mapbox://styles/mapbox/satellite-streets-v12', tags: ['3D', 'Satellite'] },
+  { name: 'Navigation Day', url: 'mapbox://styles/mapbox/navigation-day-v1', tags: ['3D', 'Apple-like'] },
+  { name: 'Navigation Night', url: 'mapbox://styles/mapbox/navigation-night-v1', tags: ['3D', 'Dark'] },
+]
+
+export const OPENFREEMAP_STYLE_PRESETS: GlStylePreset[] = [
+  { name: 'OpenFreeMap Liberty', url: OPENFREEMAP_DEFAULT_STYLE, tags: ['OpenFreeMap', '2D'] },
+  { name: 'OpenFreeMap Bright', url: 'https://tiles.openfreemap.org/styles/bright', tags: ['OpenFreeMap', 'Classic'] },
+  { name: 'OpenFreeMap Positron', url: 'https://tiles.openfreemap.org/styles/positron', tags: ['OpenFreeMap', 'Minimal'] },
+]
+
+export function getStylePresets(provider: GlMapProvider): GlStylePreset[] {
+  return provider === 'maplibre-gl' ? OPENFREEMAP_STYLE_PRESETS : MAPBOX_STYLE_PRESETS
+}
+
+export function defaultStyleForProvider(provider: GlMapProvider): string {
+  return provider === 'maplibre-gl' ? OPENFREEMAP_DEFAULT_STYLE : MAPBOX_DEFAULT_STYLE
+}
+
+export function isOpenFreeMapStyle(style?: string | null): boolean {
+  return (style || '').trim().startsWith('https://tiles.openfreemap.org/')
+}
+
+export function normalizeStyleForProvider(provider: GlMapProvider, style?: string | null): string {
+  const trimmed = (style || '').trim()
+  if (!trimmed) return defaultStyleForProvider(provider)
+  if (provider === 'maplibre-gl') {
+    return isOpenFreeMapStyle(trimmed) ? trimmed : OPENFREEMAP_DEFAULT_STYLE
+  }
+  return trimmed
+}
+
+/** The settings key that holds the style for a given GL provider. */
+export function styleSettingKey(provider: GlMapProvider): 'mapbox_style' | 'maplibre_style' {
+  return provider === 'maplibre-gl' ? 'maplibre_style' : 'mapbox_style'
+}
+
+/**
+ * Each GL provider keeps its style in its own slot (mapbox_style / maplibre_style), so
+ * switching providers never overwrites the other one's custom style. Picks and normalizes
+ * the style for the active provider.
+ */
+export function styleForActiveProvider(
+  provider: GlMapProvider,
+  mapboxStyle?: string | null,
+  maplibreStyle?: string | null,
+): string {
+  return normalizeStyleForProvider(provider, provider === 'maplibre-gl' ? maplibreStyle : mapboxStyle)
+}