refactor: move the layer state coordinator into its own module

layerState.js held both the share-link layer codec and the coordinator
that restores layer choices into the running app and persists them to
browser storage. Move the coordinator, unchanged, to
layerStateCoordinator.js so the codec stays a pure data module that code
outside the browser can use to write share links. The registry stays in
layerState.js, where the token tooling reads it, and the aircraft
barrel re-exports both.

scripts/package-boundaries.json

@@ -513,6 +513,7 @@
       "src/data/detectionPolicy.js",
       "src/data/installationFeedback.js",
       "src/data/layerState.js",
+      "src/data/layerStateCoordinator.js",
       "src/data/layerStateTokenReservations.json",
       "src/data/militaryAwarenessEngine.js",
       "src/data/scenePick.js",
@@ -834,6 +835,7 @@
       "src/data/contactMatch.js",
       "src/data/iconOrientation.js",
       "src/data/layerState.js",
+      "src/data/layerStateCoordinator.js",
       "src/data/layerStateTokenReservations.json",
       "src/data/modelVisualAnchor.js",
       "src/data/motionModel.js",
@@ -1435,6 +1437,7 @@
       "src/data/issPass.js",
       "src/data/labelArbiter.js",
       "src/data/layerState.js",
+      "src/data/layerStateCoordinator.js",
       "src/data/layerStateTokenReservations.json",
       "src/data/lifecycle.js",
       "src/data/localGeojson.js",
@@ -2611,6 +2614,7 @@
     "modules": [
       "src/data/installationFeedback.js",
       "src/data/layerState.js",
+      "src/data/layerStateCoordinator.js",
       "src/data/layerStateTokenReservations.json",
       "src/loadingFeedback.js",
       "src/navigationPolicy.js",