Improve summit terrain, mobile HUD and multiplayer night equipment

Add the Blender flashlight asset with a 600 lm beam and reduced bloom, shared-mode self badge, and compact phone controls. Relocate the summit marker, blend terrain seams, widen walking routes, and align local server configuration on port 2027.

src/scene/summitTerrain.ts

@@ -45,8 +45,20 @@ export function applySummitTerrain(geometry: BufferGeometry, meta: TerrainMetada
     const fade = 1 - t * t * (3 - 2 * t);
     positions.setY(i, positions.getY(i) + weighted / weights * fade);
     const authored = authoredHeight(x - start.x, z - start.z);
-    if (authored !== undefined) positions.setY(i, authored - meta.observerSurfaceElevation
-      - (x * x + z * z) / (2 * TERRAIN.earthRadiusMeters));
+    if (authored !== undefined) {
+      // Fade the sculpt into the corrected terrain before its rectangular edge.
+      // This also suppresses discontinuities in the exported outermost samples.
+      const localX = x - start.x, localZ = z - start.z;
+      const smooth = (distance: number) => {
+        const t = Math.min(1, Math.max(0, distance / SUMMIT_TERRAIN.plateauBlendMeters));
+        return t * t * (3 - 2 * t);
+      };
+      const blend = smooth(Math.min(localX - xs[0], xs.at(-1)! - localX))
+        * smooth(Math.min(localZ - zs[0], zs.at(-1)! - localZ));
+      const target = authored - meta.observerSurfaceElevation
+        - (x * x + z * z) / (2 * TERRAIN.earthRadiusMeters);
+      positions.setY(i, positions.getY(i) + (target - positions.getY(i)) * blend);
+    }
   }
   positions.needsUpdate = true;
   geometry.computeVertexNormals();