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>

docs/solo/navigation.md

@@ -127,6 +127,13 @@ it: GPS, the trail's distance, live shares, and the distance to the target
 >   Downloaded areas can be renamed, refreshed or deleted.
 > - **Live tiles**: with WiFi on, tiles for where you look are fetched and
 >   cached, up to the size set in Settings › Storage.
+> - **Map** (Map tools › Layers): what the map is drawn from. **Topo**
+>   (OpenTopoMap, the default), **Light** and **Dark** (Esri's grey
+>   canvases, no labels, up to zoom 16), **Satellite** (Esri World Imagery)
+>   and **Esri Topo**. Each keeps its own downloaded areas and live tiles
+>   (`/sdcard/maps-light`, `-dark`, `-sat`, `-esritopo`; Topo stays in
+>   `/sdcard/maps`). The Esri layers are meant for personal use: their terms
+>   don't cover downloading large areas.
 > - **Vector regions** (only in a build with `-D MAP_VECTOR`, unfinished):
 >   whole regions as packs made with `tools/maps/osm_vector.py`, copied to
 >   the card.