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/waterfall.js

@@ -154,24 +154,32 @@
     });
   }
 
-  function autoInit() {
-    document.querySelectorAll('[data-aksrt-waterfall]').forEach(function (el) {
+  function autoInit(root) {
+    var elements = [];
+    if (root && root.nodeType === 1 && root.matches('[data-aksrt-waterfall]')) elements.push(root);
+    Array.prototype.push.apply(elements, (root || document).querySelectorAll('[data-aksrt-waterfall]'));
+    elements.forEach(function (el) {
+      if (el._aksrtWaterfall) return;
       var cols = parseInt(el.dataset.aksrtWaterfallColumns) || 0;
       var gap = parseInt(el.dataset.aksrtWaterfallGap) || 16;
-      waterfallInstances.push(new Waterfall(el, { columns: cols, gap: gap }));
+      el._aksrtWaterfall = new Waterfall(el, { columns: cols, gap: gap });
+      waterfallInstances.push(el._aksrtWaterfall);
     });
   }
 
-  document.addEventListener('post_ajax.ed', relayoutAll);
-  document.addEventListener('aksrt:posts:rendered', relayoutAll);
-  document.addEventListener('lazyloaded', relayoutAll, true);
-
-  if (document.readyState === 'loading') {
-    document.addEventListener('DOMContentLoaded', autoInit);
-  } else {
-    autoInit();
+  function bindGlobalEvents() {
+    if (document.__aksrtWaterfallEventsBound) return;
+    document.__aksrtWaterfallEventsBound = true;
+    document.addEventListener('post_ajax.ed', relayoutAll);
+    document.addEventListener('aksrt:posts:rendered', relayoutAll);
+    document.addEventListener('lazyloaded', relayoutAll, true);
   }
 
+  window.AksrtFrontend.register('aksrt-waterfall', function (root) {
+    bindGlobalEvents();
+    autoInit(root);
+  });
+
   // Export to global
   window.AksrtWaterfall = Waterfall;
   window.AksrtInfiniteScroll = InfiniteScroll;