重构 monorepo 并完善网页端订阅与首页体验

- 迁移为 frontend-web、frontend-electron、backend-web 与 docker 部署结构
- 网页端：订阅门禁二次弹窗、套餐/支付组件化、顶栏分组对齐
- 首页：最近文件与模板库布局优化，缩略图对齐，下载与删除操作
- 新增管理后台、支付与云端文件 API，更新 README 与项目规范

Co-authored-by: Cursor <cursoragent@cursor.com>

frontend-web/js/common/soon-toast.js

@@ -0,0 +1,20 @@
+(function () {
+  'use strict';
+
+  function soonToast(message, type) {
+    if (typeof layer === 'undefined' || !layer.msg) return;
+    var skin = 'soon-toast';
+    if (type === 'success') skin += ' soon-toast--success';
+    else if (type === 'error') skin += ' soon-toast--error';
+    else if (type === 'warn') skin += ' soon-toast--warn';
+    layer.msg(message, {
+      time: 2400,
+      shade: 0,
+      offset: '72px',
+      icon: -1,
+      skin: skin
+    });
+  }
+
+  window.soonToast = soonToast;
+})();