feat(world3d): a property's models in capture and recorded replays

In a capture replay, each model stands where the capture saw it at the
playhead (the UGC server's mesh for a brick built model when it has one, a box
otherwise), appearing, moving and vanishing with the timeline both ways; the
Property tab shows the property data of that moment and the models standing,
and behavior messages are ticks on the timeline. In a replay of recorded
positions on one property instance, the models placed now are drawn and
labelled as now.

Co-Authored-By: Claude Opus 5.5 <noreply@anthropic.com>

dDashboardServer/static/js/lddviewer.js

@@ -148,7 +148,7 @@ export function parseLxfml(text) {
  * The parts of a model the UGC server made (a .nif, converted by the dashboard like the scenery's models: see
  * scenery-core.js), as [{geometry, material}] in the model's own coordinates. Each part owns its geometry and material.
  */
-async function loadGeneratedModel(url) {
+export async function loadGeneratedModel(url) {
 	const response = await limitedFetch(url);
 	if (!response.ok) throw new Error('HTTP ' + response.status);
 	const model = parseModel(await response.arrayBuffer());