fix(typesetting): 修复SnapDOM全局

- SnapDOM v2.12.0 IIFE构建非真正IIFE，function $/let .$
- 加载snapdom.js前保存jQuery的
- 加载后立即恢复jQuery的$
- 集成测试通过: 21页排版正常，纯图片页有brand header+页码
- Console零JS错误，排版耗时约2秒

view/admin/post/phone_image.html

@@ -279,7 +279,9 @@
     <script src="/static/lib/jquery/jquery-3.4.1.min.js"></script>
     <script src="/static/lib/layui/layui.js"></script>
     <script src="/static/lib/wangeditor/index.js"></script>
+    <script>var _saved_jQuery_dollar = window.$;</script>
     <script src="/static/lib/snapdom/snapdom.js"></script>
+    <script>if (window._saved_jQuery_dollar) window.$ = window._saved_jQuery_dollar;</script>
     <script src="/static/js/phone-image.js"></script>
     <script>
         layui.use(['form', 'layer'], function () {