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/core/comment-fixed-input.js

@@ -39,19 +39,6 @@
     }
   }
 
-  document.addEventListener('click', function (e) {
-    var trigger = e.target && e.target.closest ? e.target.closest('[fixed-input]') : null;
-    if (!trigger) return;
-    e.preventDefault();
-    var targetSel = trigger.getAttribute('fixed-input') || '#respond';
-    var panel = document.querySelector(targetSel);
-    var comments = document.getElementById('comments');
-    if (comments && comments.scrollIntoView) {
-      comments.scrollIntoView({ behavior: 'smooth', block: 'start' });
-    }
-    FixedInput(panel, 'show');
-  });
-
   // Autoheight textareas.
   function bindAutoheight(ta) {
     if (!ta || ta.dataset.autoheightBound) return;
@@ -67,24 +54,49 @@
     resize();
   }
 
-  function scan() {
-    document.querySelectorAll('textarea[autoheight], textarea.grin').forEach(bindAutoheight);
+  function scopeFor(root) {
+    return root && root.querySelectorAll ? root : document;
   }
 
-  document.addEventListener('DOMContentLoaded', scan);
-  if (window.AksrtFrontend && typeof window.AksrtFrontend.register === 'function') {
-    window.AksrtFrontend.register('aksrt-comment-fixed-input', function (root) {
-      scan();
-      // Expose for submit hide.
-      root = root || document;
-      var respond = root.querySelector ? root.querySelector('#respond') : document.getElementById('respond');
-      if (respond) {
-        respond.aksrtFixedInput = function (action) {
-          FixedInput(respond, action);
-        };
+  function scan(root) {
+    var scope = scopeFor(root);
+    if (scope.nodeType === 1 && scope.matches('textarea[autoheight], textarea.grin')) {
+      bindAutoheight(scope);
+    }
+    scope.querySelectorAll('textarea[autoheight], textarea.grin').forEach(bindAutoheight);
+  }
+
+  var globalsBound = false;
+  function bindGlobals() {
+    if (globalsBound) return;
+    globalsBound = true;
+    document.addEventListener('click', function (e) {
+      var trigger = e.target && e.target.closest ? e.target.closest('[fixed-input]') : null;
+      if (!trigger) return;
+      e.preventDefault();
+      var targetSel = trigger.getAttribute('fixed-input') || '#respond';
+      var panel = document.querySelector(targetSel);
+      var comments = document.getElementById('comments');
+      if (comments && comments.scrollIntoView) {
+        comments.scrollIntoView({ behavior: 'smooth', block: 'start' });
       }
+      FixedInput(panel, 'show');
     });
   }
 
+  window.AksrtFrontend.register('aksrt-comment-fixed-input', function (root, reason) {
+    bindGlobals();
+    scan(root);
+    root = root || document;
+    var respond = root.nodeType === 1 && root.matches && root.matches('#respond')
+      ? root
+      : (root.querySelector ? root.querySelector('#respond') : document.getElementById('respond'));
+    if (respond) {
+      respond.aksrtFixedInput = function (action) {
+        FixedInput(respond, action);
+      };
+    }
+  });
+
   window.AksrtFixedInput = FixedInput;
 })();