feat: Add wheelchair to avatar customization

common/script/content/appearance/index.js

@@ -3,6 +3,7 @@ import shirts from './shirt.js';
 import skins from './skin.js';
 import sizes from './size.js';
 import backgrounds from './backgrounds.js';
+import chairs from './chair.js';
 import {forOwn, clone} from 'lodash';
 
 let reorderedBgs = {};
@@ -25,6 +26,7 @@ let appearances = {
   shirt: shirts,
   size: sizes,
   skin: skins,
+  chair: chairs,
   background: reorderedBgs,
 };