feat(map): add synthetic moving target layer

docs/MAP_CESIUM_REACT_ADAPTER.md

@@ -68,3 +68,25 @@ recreates the local Cesium viewer and never changes the TileCache write intent.
 
 The package never creates browser, application, Docker or per-user TileCache
 storage.
+
+## Optional synthetic target layer
+
+The adapter accepts an optional provider-neutral Ghost Pin layer for bounded
+product sandboxes. It uses the canonical `elevated-spike` presentation:
+terrain-relative stem, outlined head, label plate and independent camera-height
+visibility for target and label. The layer is controlled by the existing
+`targets` visibility flag and does not create a Data Product, Engine command or
+authoritative `map.moving_object`.
+
+Consumers own generation, persistence and explicit removal of synthetic
+positions. The adapter only:
+
+- resolves the centre of the current visible globe through its imperative
+  `getViewAnchor()` handle;
+- renders declared numeric positions;
+- advances optional motion inside the declared radius; and
+- returns the current positions through `snapshotGhostPins()` for an explicit
+  product save.
+
+Motion never recreates the Cesium viewer or any provider. A renderer teardown
+stops its single animation frame loop.