Fix Three.js import map (admin/viewer black canvas)

public/index.html

@@ -25,6 +25,14 @@
     <div class="row">link: <span id="status" class="warn">connecting…</span> · ghosts: <b id="count">0</b></div>
     <div class="row">drag to orbit · scroll to zoom</div>
   </div>
+  <script type="importmap">
+  {
+    "imports": {
+      "three": "https://cdn.jsdelivr.net/npm/three@0.160.0/build/three.module.js",
+      "three/addons/": "https://cdn.jsdelivr.net/npm/three@0.160.0/examples/jsm/"
+    }
+  }
+  </script>
   <script type="module" src="js/viewer.js"></script>
 </body>
 </html>