fix(widgets): dispatch close event before registry cleanup

Move widget:close dispatch before _widgets.delete() so handlers can
still query WidgetManager for the widget's state during the event.

Co-Authored-By: Claude Opus 4.6 <noreply@anthropic.com>

src/js/widgets.js

@@ -165,8 +165,8 @@ const WidgetManager = {
     const entry = this._widgets.get(id);
     if (!entry) return;
     entry.el.remove();
-    this._widgets.delete(id);
     this._emitter.dispatchEvent(new CustomEvent('widget:close', { detail: { id } }));
+    this._widgets.delete(id);
   },
 
   /**