chore: 将后端移动到 api/ 目录，准备合并为单仓库

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

api/static/admin/js/popup_response.js

@@ -0,0 +1,15 @@
+'use strict';
+{
+    const initData = JSON.parse(document.getElementById('django-admin-popup-response-constants').dataset.popupResponse);
+    switch(initData.action) {
+    case 'change':
+        opener.dismissChangeRelatedObjectPopup(window, initData.value, initData.obj, initData.new_value);
+        break;
+    case 'delete':
+        opener.dismissDeleteRelatedObjectPopup(window, initData.value);
+        break;
+    default:
+        opener.dismissAddRelatedObjectPopup(window, initData.value, initData.obj);
+        break;
+    }
+}