feat: relay station masts come online through the toolkit chapter

src/scene/world/environment.ts

@@ -38,7 +38,8 @@ import { createHeadlights } from '@/scene/world/headlights';
 import { maintenanceProgress } from '@/journey/maintenance-progress';
 import { createMilestones } from '@/scene/world/milestones';
 import { billboardNear, createBillboard, textureSize } from '@/scene/world/billboard';
-import { BILLBOARD_NUDGE } from '@/scene/world/composition';
+import { BILLBOARD_NUDGE, RELAY_NUDGE } from '@/scene/world/composition';
+import { createRelayMasts } from '@/scene/world/relay-masts';
 import { isMilestoneSection, sectionLocalProgress } from '@/journey/route-log';
 import { dawnStep, type DawnStep } from '@/journey/dawn';
 import { dawnLightUniforms } from '@/scene/world/dawn-light';
@@ -185,7 +186,15 @@ export async function createProceduralSceneGeneration(
     textureSize: textureSize(context.quality),
   });
   let billboardKey = '';
+  // RELAY STATION: transmitter masts come online through Toolkit. Low tier,
+  // touch and data saver: all rungs lit, steady beacons, no beams, hover or tone.
+  const relay = createRelayMasts(
+    context.resources,
+    maintenanceTier === 'full'
+      && (globalThis.navigator as { connection?: { saveData?: boolean } } | undefined)?.connection?.saveData !== true,
+  );
   scene.add(
+    relay.group,
     billboard.mesh,
     maintenance.group,
     milestones.mesh,
@@ -380,6 +389,15 @@ export async function createProceduralSceneGeneration(
         musicPulse,
         deltaSeconds,
       );
+      const relayNudge = relay.update(
+        snapshot.activeSectionId,
+        snapshot.activeSectionId === 'toolkit' ? sectionLocalProgress(snapshot, 'toolkit') : null,
+        musicPulse,
+        document.documentElement.dataset.relayFocus,
+        deltaSeconds,
+        now,
+        camera.aspect,
+      );
       const billboardNudge = billboard.update({
         section: snapshot.activeSectionId,
         p: snapshot.activeSectionId === 'selected-builds'
@@ -533,7 +551,7 @@ export async function createProceduralSceneGeneration(
           baseComposition.targetY,
           upcoming.targetY,
           anticipation,
-        ),
+        ) + RELAY_NUDGE.targetY * relayNudge,
         targetZ: THREE.MathUtils.lerp(
           baseComposition.targetZ,
           upcoming.targetZ,