Explore places on the map, planner route fixes, and instance-wide Mapbox (#1147)

* feat(maps): add an OSM POI search endpoint (category within a viewport)

New /api/maps/pois queries OpenStreetMap via Overpass for places of a category
(restaurants, cafes, hotels, sights, …) inside a bounding box. OSM-only by design
— it never calls Google, even when a Google key is configured.

* feat(map): explore nearby places on the trip map (OSM category pill)

A floating, icon-only pill over the planner map lets you toggle a POI category and
see those OpenStreetMap places in the current view; clicking a marker opens the
add-place form pre-filled (name, address, website, phone). Single-select with a
'search this area' action after the map moves. Renders on both the Leaflet and
Mapbox maps, and can be turned off in settings (discussion #841).

* fix(planner): anchor timed places when optimising and route transports by location

- The day optimiser no longer reshuffles places that have a set time — they stay
  anchored to their time, like locked places.
- The route now uses a transport's departure/arrival location as a waypoint when it
  has one (e.g. a flight's airport), instead of breaking the route at every booking;
  transports without a location are ignored for routing but still show their leg's
  distance/duration under the booking.

* feat(admin): instance-wide Mapbox defaults in default user settings

Admins can set a shared Mapbox token (plus style, 3D and quality) as instance
defaults, so the whole instance can use Mapbox without each user pasting their own
key. Users without their own value inherit it via the existing admin-defaults
merge; the shared token is stored encrypted (discussion #920).

shared/src/i18n/fr/admin.ts

@@ -388,5 +388,15 @@ const admin: TranslationStrings = {
     "Supprime toutes les passkeys de cet utilisateur (ex. en cas d'appareil perdu). Il pourra toujours se connecter avec son mot de passe.",
   'admin.passkey.resetConfirm': 'Supprimer toutes les passkeys de {name} ?',
   'admin.passkey.resetDone': '{count} passkey(s) supprimée(s)',
+  'admin.defaultSettings.mapProvider': 'Moteur cartographique',
+  'admin.defaultSettings.mapProviderHint': 'La carte par défaut pour tous les utilisateurs de cette instance. Chaque utilisateur peut toujours la remplacer dans ses propres paramètres.',
+  'admin.defaultSettings.providerLeaflet': 'Standard (gratuit)',
+  'admin.defaultSettings.providerMapbox': 'Mapbox (3D)',
+  'admin.defaultSettings.mapboxToken': 'Jeton Mapbox partagé',
+  'admin.defaultSettings.mapboxTokenHint': 'Utilisé pour chaque utilisateur n\'ayant pas saisi son propre jeton — ainsi toute l\'instance bénéficie de Mapbox sans partager la clé individuellement. Stocké de façon chiffrée.',
+  'admin.defaultSettings.mapboxStyle': 'Style de carte',
+  'admin.defaultSettings.mapboxStylePlaceholder': 'Choisissez un style…',
+  'admin.defaultSettings.mapbox3d': 'Bâtiments & terrain en 3D',
+  'admin.defaultSettings.mapboxQuality': 'Mode haute qualité',
 };
 export default admin;