feat(frontend): align single post page 1:1 with Zibll

Restore Zibll float dual-column shell, fix single settings DTO key mapping,
reorder article footer/actions, and match author bar, prev/next, title/body
typography, and limit-height expand UX.

assets/css/frontend/single-post/related-toc.css

@@ -1,3 +1,47 @@
+/* ===== Zibll article-nav (prev/next) ===== */
+.article-nav {
+  display: block;
+  width: 100%;
+}
+
+.article-nav .box-body {
+  width: calc(50% - 7px);
+  margin: 0;
+  display: inline-block;
+  vertical-align: top;
+}
+
+.article-nav .box-body + .box-body {
+  margin-right: 0;
+  float: right;
+  text-align: right;
+}
+
+.article-nav a {
+  display: block;
+  color: inherit;
+  text-decoration: none;
+}
+
+.article-nav a:hover {
+  color: var(--focus-color, #f04494);
+}
+
+.article-nav .text-ellipsis-2 {
+  display: -webkit-box;
+  -webkit-line-clamp: 2;
+  -webkit-box-orient: vertical;
+  overflow: hidden;
+  font-size: 14px;
+  line-height: 1.5;
+  color: var(--key-color, #333);
+}
+
+.article-nav p {
+  margin: 0 0 6px;
+  font-size: 12px;
+}
+
 /* ===== Previous / Next Navigation ===== */
 .post-nav-box {
     display: grid;
@@ -112,12 +156,45 @@
 /* ===== Comment Card Spacing ===== */
 .comments-card { margin-bottom: 16px; }
 
-/* ===== Content Height Clamp ===== */
+/* ===== Content Height Clamp (Zibll) ===== */
+.limit-height,
 .wp-posts-content.limit-height {
     position: relative;
     overflow: hidden;
 }
 
+.limit-height .read-more {
+    position: absolute;
+    bottom: 0;
+    width: 100%;
+    text-align: center;
+    background-image: linear-gradient(0deg, var(--main-bg-color, #fff) 70px, rgba(255, 255, 255, 0) 100%);
+    animation: lazy_fade 0.5s;
+    z-index: 80;
+}
+
+html.dark .limit-height .read-more,
+body.dark-theme .limit-height .read-more {
+    background-image: linear-gradient(0deg, var(--main-bg-color, #2a2a2a) 70px, rgba(53, 54, 55, 0) 100%);
+}
+
+.limit-height .read-more a,
+.limit-height .read-more .read-more-open {
+    padding: 25px 0;
+    display: inline-block;
+    color: var(--focus-color, #f04494);
+    margin-top: 80px;
+    cursor: pointer;
+    background: none;
+    border: 0;
+    font-size: 14px;
+}
+
+@keyframes lazy_fade {
+  from { opacity: 0; }
+  to { opacity: 1; }
+}
+
 .wp-posts-content.limit-height::after {
     content: '';
     position: absolute;