feat(runtime): 全站前端脚本统一接入 AksrtFrontend 全局 DOM 生命周期

- rehydrate.js 新增 boot()/aksrt:ready 事件，支持 boot 后晚注册立即以 init 触发
- aksrt-runtime.js 初始加载改走 AksrtFrontend.boot，tooltip/倒计时注册为组件
- 约 30 个前端脚本（首页、评论、支付、路由、页面叶子、widgets）
  从直接 DOMContentLoaded 迁移为 AksrtFrontend.register，并加幂等标记
- section-navs 依赖改为 aksrt-runtime，保证注册时序
- 清理死代码：删除孤儿 loader.js/main.js 及 runtime/page-navs 遗留副本
- loader.js 移除已迁移模块的 tbquire 路径映射，main.js 相应瘦身
- build-public-assets.mjs 增加 runtime/main.min.js 自动压缩步骤
- 新增 4 个契约测试（homepage-dom/rehydrate-runtime/global-dom-init/
  public-bundle-parity），3 个既有 harness 适配注册表初始化方式

assets/js/poster-share.js

@@ -37,7 +37,11 @@
   PosterShare.prototype.init = function () {
     var self = this;
 
-    document.querySelectorAll(this.options.triggerSelector).forEach(function (btn) {
+    var scope = this.options.root || document;
+    var triggers = [];
+    if (scope.nodeType === 1 && scope.matches(this.options.triggerSelector)) triggers.push(scope);
+    Array.prototype.push.apply(triggers, scope.querySelectorAll(this.options.triggerSelector));
+    triggers.forEach(function (btn) {
       btn.addEventListener('click', function (e) {
         e.preventDefault();
 
@@ -360,25 +364,21 @@
   };
 
   // 自动初始化
-  function autoInit() {
-    document.querySelectorAll('[data-aksrt-poster]').forEach(function (el) {
-      if (el.dataset.posterInit) return;
+  function autoInit(root) {
+    var triggers = [];
+    if (root && root.nodeType === 1 && root.matches('[data-aksrt-poster]')) triggers.push(root);
+    Array.prototype.push.apply(triggers, (root || document).querySelectorAll('[data-aksrt-poster]'));
+    if (!triggers.length) return;
+    var pending = triggers.filter(function (el) { return el.dataset.posterInit !== '1'; });
+    if (!pending.length) return;
+    var instance = new PosterShare({ root: root || document, triggerSelector: '[data-aksrt-poster]' });
+    pending.forEach(function (el) {
       el.dataset.posterInit = '1';
-
-      var config = {};
-      try {
-        config = JSON.parse(el.dataset.aksrtPoster || '{}');
-      } catch (e) {}
-
-      new PosterShare({ triggerSelector: '[data-aksrt-poster]' });
+      el._aksrtPosterShare = instance;
     });
   }
 
-  if (document.readyState === 'loading') {
-    document.addEventListener('DOMContentLoaded', autoInit);
-  } else {
-    autoInit();
-  }
+  window.AksrtFrontend.register('aksrt-poster-share', autoInit);
 
   /**
    * Generate a poster directly from a unified share payload, without binding