feat(nav): rewrite top header to zibll 1:1 DOM/CSS/JS contract

Replace hybrid site-nav/drawer shell with zibll navbar-top layouts 1/2/3,
body.mobile-navbar-show drawer, wired NavWalker + aksrt_menu_options meta,
nav_folding/chevron, VIP switches, and SPA/PHP schema parity. No dual-class
compat paths.

assets/js/core/nav.js

@@ -1,54 +1,88 @@
 /**
- * AKSRT Navigation Drawer
+ * AKSRT nav chrome — zibll contract (body.mobile-navbar-show, folding, chevron).
+ * Drawer open/close is handled by aksrt-runtime [data-toggle-class].
  */
 (function () {
   "use strict";
 
-  function initNavDrawer() {
-    var toggle = document.getElementById("nav-toggle");
-    var drawer = document.getElementById("nav-drawer");
-    var backdrop = document.getElementById("nav-drawer-backdrop");
-    var closeBtn = document.getElementById("nav-drawer-close");
-    if (!toggle || !drawer || !backdrop) return;
+  function appendChevrons() {
+    document.querySelectorAll(".navbar-top li.menu-item-has-children > a").forEach(function (a) {
+      if (a.querySelector(".fa-angle-down")) return;
+      var i = document.createElement("i");
+      i.className = "fa fa-angle-down ml6";
+      i.setAttribute("aria-hidden", "true");
+      a.appendChild(i);
+    });
+  }
 
-    var openIcon = toggle.querySelector(".nav-toggle-open");
-    var closeIcon = toggle.querySelector(".nav-toggle-close");
+  function navFolding() {
+    var collapse = document.querySelector(".navbar-collapse");
+    var nav = document.querySelector(".navbar-nav");
+    if (!collapse || !nav) return;
+    if (window.innerWidth <= 996) return;
 
-    function setOpen(open) {
-      toggle.setAttribute("aria-expanded", open ? "true" : "false");
-      drawer.classList.toggle("is-open", open);
-      backdrop.classList.toggle("is-open", open);
-      drawer.setAttribute("aria-hidden", open ? "false" : "true");
-      backdrop.setAttribute("aria-hidden", open ? "false" : "true");
-      document.body.style.overflow = open ? "hidden" : "";
-      if (openIcon && closeIcon) {
-        openIcon.style.display = open ? "none" : "";
-        closeIcon.style.display = open ? "" : "none";
+    var header = document.querySelector(".header");
+    if (header && header.offsetHeight <= 81) return;
+
+    // Already folded?
+    if (nav.querySelector("li.aksrt-nav-more")) return;
+
+    var surplus = collapse.clientWidth;
+    Array.prototype.forEach.call(collapse.children, function (child) {
+      if (!child.classList.contains("navbar-nav")) {
+        surplus -= child.offsetWidth || 0;
       }
-      if (open && typeof window.__aksrtCloseSearchPanel === "function") {
-        window.__aksrtCloseSearchPanel();
+    });
+    var headerEl = document.querySelector(".navbar-header");
+    surplus -= (headerEl ? headerEl.offsetWidth : 0) + 40;
+
+    var navsWidth = 66;
+    var foldItems = [];
+    Array.prototype.forEach.call(nav.children, function (li) {
+      navsWidth += li.offsetWidth || 0;
+      if (navsWidth > surplus) {
+        foldItems.push(li);
       }
-    }
-
-    setOpen(false);
-
-    toggle.addEventListener("click", function () {
-      setOpen(!drawer.classList.contains("is-open"));
-    });
-    backdrop.addEventListener("click", function () {
-      setOpen(false);
-    });
-    if (closeBtn) closeBtn.addEventListener("click", function () {
-      setOpen(false);
     });
+    if (!foldItems.length) return;
 
+    var more = document.createElement("li");
+    more.className = "menu-item menu-item-has-children aksrt-nav-more";
+    more.innerHTML =
+      '<a href="javascript:void(0);"><i class="fas fa-bars" aria-hidden="true"></i></a><ul class="sub-menu"></ul>';
+    var sub = more.querySelector(".sub-menu");
+    foldItems.forEach(function (li) {
+      sub.appendChild(li);
+    });
+    nav.appendChild(more);
+  }
+
+  function bindDrawerA11y() {
+    // Esc closes mobile nav via body class.
     document.addEventListener("keydown", function (e) {
-      if (e.key === "Escape" && drawer.classList.contains("is-open")) {
-        setOpen(false);
-        toggle.focus();
+      if (e.key === "Escape" && document.body.classList.contains("mobile-navbar-show")) {
+        document.body.classList.remove("mobile-navbar-show");
       }
     });
   }
 
-  window.AksrtFrontend.register("aksrt-nav-drawer", function () { initNavDrawer(); });
+  function init() {
+    appendChevrons();
+    try {
+      navFolding();
+    } catch (err) {
+      // ignore fold failures
+    }
+    bindDrawerA11y();
+  }
+
+  if (window.AksrtFrontend && typeof window.AksrtFrontend.register === "function") {
+    window.AksrtFrontend.register("aksrt-nav-chrome", function () {
+      init();
+    });
+  } else if (document.readyState === "loading") {
+    document.addEventListener("DOMContentLoaded", init);
+  } else {
+    init();
+  }
 })();