Offline search and routing for tile schemas besides OpenMapTiles

Offline search and routing read place names and roads from downloaded vector tiles (offline/extract.ts). Map search reads loaded tiles the same way (search/SearchEngine.ts). Both assume the OpenMapTiles schema: layer names like poi, place, transportation and transportation_name, plus its attributes.

Tiles from Protomaps (roads, pois, places), Mapbox Streets v8 or Shortbread still draw and download offline, but aren't searchable or routable.

Scope

• A schema description: layer names plus attribute mapping (class/kind, name, oneway, rank, brunnel/level). The built-in OpenMapTiles mapping is the default.
• Mappings for Protomaps and Shortbread, and one for Mapbox Streets v8.
• Pass the schema through OfflineMaps and SearchEngine. The basemap style already has a sourceLayers remap option to align with.
• Tests with a small fixture per schema.