feat(map): base layers - Topo, Light, Dark, Satellite, Esri Topo

Map tools > Layers > Map picks what the map is drawn from:
- Topo: OpenTopoMap, as before.
- Light and Dark: Esri's grey canvases, no labels, up to z16.
- Satellite: Esri World Imagery.
- Esri Topo.

Each layer has its own folder for downloaded areas (/sdcard/maps-light,
-dark, -sat, -esritopo; Topo stays in /sdcard/maps) and its own live-tile
cache. Live-cache records carry the layer.

Esri serves JPEG: decoded with LVGL's tjpgd (LV_USE_TJPGD), whatever the
file name says. The layer is kept in NVS (mc_ui/layer); switching waits
while a download or a deletion runs in the current folder.

Co-Authored-By: Claude Opus 5.5 <noreply@anthropic.com>

examples/companion_radio/ui-lvgl/UITask.h

@@ -169,6 +169,7 @@ public:
   void setLiveTiles(bool on);
   void setTrails(bool on);
   void setVectorMap(bool on);
+  void setMapLayer(int i);
   void simMapAt(const char* spec);      // Map tools > Live tiles
   void simCompose(const char* text);    // the open thread's field: this text, keyboard up
   void simDm();                         // the first chat contact's thread