fix(skin): cache-bust query ?v=20260614 for character-assets URLs

After backend CORS rollout users had stale CORS-failure cached for
Mixamo GLB. Adding a query suffix forces browsers to re-fetch the URL
instead of replaying the cached failure.

Co-Authored-By: Claude Opus 4.7 <noreply@anthropic.com>

src/editor/engine/PlayerController.js

@@ -687,7 +687,7 @@ export class PlayerController {
                     ? 'http://localhost:3000'
                     : 'https://rublox.pro';
                 return {
-                    file: `${base}/character-assets/skins/${typeId}.glb`,
+                    file: `${base}/character-assets/skins/${typeId}.glb?v=20260614`,
                     isR15: false,
                     kind: 'non-humanoid-rigged',
                     overrides: {},