Split Open Map Overlays into Sea Marks and Ski Pistes layers

Each overlay is now its own Infrastructure row instead of a chip on one
shared row: sea-marks (token 6) and ski-pistes (token 7), both
enabled-only, built by createOsmOverlayLayers() from one descriptor
list. Drops the option group and its share-codec defaults, gives each
layer its own name, voice entry and CURRENT-STATE row, and shifts the
token-ledger fixtures to the next free digit 8.

changelog.d/114-open-map-overlays.md

@@ -1,4 +1,3 @@
-- Add Open Map Overlays (Infrastructure ▸ Open Map Overlays): OpenSeaMap sea
-  marks and OpenSnowMap ski pistes as two toggleable raster overlays. They
-  drape on the globe stacks and on Google 3D, and share links keep the row and
-  both chips (Tom-Neverwinter, #114).
+- Add Sea Marks (OpenSeaMap) and Ski Pistes (OpenSnowMap) as two raster
+  overlay layers under Infrastructure. They drape on the globe stacks and on
+  Google 3D, and share links keep each one (Tom-Neverwinter, #114).