feat: expose stable journey intent signals

src/scene/create-scene-controller.ts

@@ -582,6 +582,13 @@ function copyJourneySnapshot(snapshot: JourneySnapshot): JourneySnapshot {
         : {}),
     } : null,
     arrived: Boolean(snapshot.arrived),
+    sectionActivation: {
+      layoutRevision: snapshot.sectionActivation.layoutRevision,
+      activeHeadingOffsetVh: finite(snapshot.sectionActivation.activeHeadingOffsetVh),
+      nextHeadingOffsetVh: snapshot.sectionActivation.nextHeadingOffsetVh === null
+        ? null
+        : finite(snapshot.sectionActivation.nextHeadingOffsetVh),
+    },
   };
 }
 
@@ -600,6 +607,11 @@ function initialJourneySnapshot(): JourneySnapshot {
     chapter: 'deep-night',
     sign: null,
     arrived: false,
+    sectionActivation: {
+      layoutRevision: 0,
+      activeHeadingOffsetVh: 0,
+      nextHeadingOffsetVh: null,
+    },
   };
 }