feat(map): adopt DC Default scene

docs/21_MISSION_CORE_MAP_PAGE_INTEGRATION_PLAN.md

@@ -194,8 +194,22 @@ the existing Gateway is reachable and reports a configured state.
 
 ## Map state contract
 
-Add a versioned Mission Core map document outside operator environment media,
-for example `missioncore.map-view/v1`, with optimistic revision:
+Mission Core stores a versioned map document outside operator environment
+media. The implemented contract is `missioncore.map-view/v2`, with optimistic
+revision:
+
+- its default camera and complete visual state are the canonical Foundry
+  `DC Default` profile;
+- black-and-white presentation is produced by zero imagery saturation while
+  imagery remains active;
+- atmosphere, fog, sun, shadows, terrain, buildings and the elevated LOD grid
+  are persisted as provider-neutral values;
+- saved `missioncore.map-view/v1` documents are upgraded in memory and become
+  v2 on the next explicit save;
+- provider attribution remains registered in the renderer. The local
+  experiment may hide only the visual credit overlay through
+  `MISSIONCORE_MAP_SANDBOX_HIDE_CREDITS=1`; production defaults to visible
+  credits and must not enable that sandbox flag.
 
 - camera: longitude, latitude, height, heading, pitch and roll;
 - provider-neutral visual settings compatible with Map Page;