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.

package.json

@@ -25,7 +25,8 @@
     "format:check": "npm run format:check --workspace=shared && npm run format:check --workspace=server && npm run format:check --workspace=client"
   },
   "devDependencies": {
-    "concurrently": "^10.0.3"
+    "concurrently": "^10.0.3",
+    "unrun": "^0.3.1"
   },
   "comment:overrides": "Force a single React 19 across the workspace so the test renderer (@testing-library/react) and the app share one react-dom.",
   "overrides": {
@@ -34,9 +35,9 @@
     "multer": "^2.2.0"
   },
   "optionalDependencies": {
-    "@rollup/rollup-linux-x64-musl": "4.62.0",
-    "@rollup/rollup-linux-arm64-musl": "4.62.0",
+    "@img/sharp-linuxmusl-arm64": "0.35.1",
     "@img/sharp-linuxmusl-x64": "0.35.1",
-    "@img/sharp-linuxmusl-arm64": "0.35.1"
+    "@rollup/rollup-linux-arm64-musl": "4.62.0",
+    "@rollup/rollup-linux-x64-musl": "4.62.0"
   }
 }