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/vendor/select2/i18n/en.js

@@ -0,0 +1,3 @@
+/*! Select2 4.0.13 | https://github.com/select2/select2/blob/master/LICENSE.md */
+
+!function(){if(jQuery&&jQuery.fn&&jQuery.fn.select2&&jQuery.fn.select2.amd)var e=jQuery.fn.select2.amd;e.define("select2/i18n/en",[],function(){return{errorLoading:function(){return"The results could not be loaded."},inputTooLong:function(e){var n=e.input.length-e.maximum,r="Please delete "+n+" character";return 1!=n&&(r+="s"),r},inputTooShort:function(e){return"Please enter "+(e.minimum-e.input.length)+" or more characters"},loadingMore:function(){return"Loading more results…"},maximumSelected:function(e){var n="You can only select "+e.maximum+" item";return 1!=e.maximum&&(n+="s"),n},noResults:function(){return"No results found"},searching:function(){return"Searching…"},removeAllItems:function(){return"Remove all items"}}}),e.define,e.require}();