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.

src/data/layerStateTokenReservations.json

@@ -17,12 +17,13 @@
   ["military", "m"],
   ["military-awareness", "g"],
   ["military-installations", "i"],
-  ["osm-overlays", "6"],
   ["radio", "r"],
   ["recent-imagery", "1"],
   ["rocket-launches", "x"],
   ["s2-ghostmaps", "5"],
   ["satellites", "s"],
+  ["sea-marks", "6"],
+  ["ski-pistes", "7"],
   ["street-level", "0"],
   ["telegeography-submarine-cables", "u"],
   ["traffic", "t"],