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/asset-base.js

@@ -0,0 +1,41 @@
+(function () {
+  'use strict';
+
+  function computeAssetBase() {
+    if (typeof window === 'undefined' || !window.location) {
+      return 'assets/images/';
+    }
+    var p = window.location.pathname || '/';
+    if (p.indexOf('/pages/') !== -1 || /\.web\.html$/i.test(p) || /\/pages\/[^/]+\.html$/i.test(p)) {
+      return '../assets/images/';
+    }
+    if (p.endsWith('/pages/') || p.endsWith('/pages')) {
+      return '../assets/images/';
+    }
+    return 'assets/images/';
+  }
+
+  function computeJsBase() {
+    if (typeof window === 'undefined' || !window.location) {
+      return 'js/';
+    }
+    var p = window.location.pathname || '/';
+    if (p.indexOf('/pages/') !== -1 || /\.web\.html$/i.test(p) || /\/pages\/[^/]+\.html$/i.test(p)) {
+      return '../js/';
+    }
+    return 'js/';
+  }
+
+  window.SOON_ASSET_BASE = computeAssetBase();
+  window.SOON_JS_BASE = computeJsBase();
+
+  window.soonAsset = function (name) {
+    var n = String(name || '').replace(/^\/+/, '');
+    return window.SOON_ASSET_BASE + n;
+  };
+
+  window.soonJs = function (rel) {
+    var n = String(rel || '').replace(/^\/+/, '');
+    return window.SOON_JS_BASE + n;
+  };
+})();