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/author-actions.css

@@ -440,3 +440,103 @@ html.dark .post-drop-meta__item:hover {
 .author-box__posts a:hover { color: var(--color-primary); }
 .author-box__posts a::before { content: '\2022'; color: var(--color-primary); }
 
+
+
+/* ===== Zibll single-metabox / author bar ===== */
+.article-avatar .user-info {
+  width: 100%;
+}
+
+.article-avatar .avatar-img img,
+.article-avatar .avatar {
+  width: 42px;
+  height: 42px;
+  border-radius: 50%;
+  object-fit: cover;
+}
+
+.article-avatar .display-name {
+  font-weight: 600;
+  color: var(--key-color, #333);
+}
+
+.article-header .article-avatar .relative {
+  margin-top: 20px;
+}
+
+.single-metabox {
+  right: 0;
+  font-size: 15px;
+  --meta-color: var(--muted-color, #777);
+}
+
+.single-metabox .post-metas {
+  background: var(--body-bg-color, #f5f5f5);
+  right: 0;
+  padding: 2px 6px;
+  border-radius: 100px;
+  color: var(--meta-color);
+  display: inline-flex;
+  flex-wrap: wrap;
+  align-items: center;
+  gap: 0;
+}
+
+.single-metabox .post-metas item {
+  margin: 0 6px;
+  font-size: 13px;
+}
+
+.single-metabox .post-drop-meta {
+  position: relative;
+  display: inline-block;
+}
+
+.single-metabox.cover-meta {
+  font-size: 14px;
+  right: 1em;
+  top: 1.6em;
+  --meta-color: rgba(255, 255, 255, 0.8);
+  --body-bg-color: rgba(0, 0, 0, 0.3);
+}
+
+.line-form-line {
+  display: block;
+  height: 1px;
+  background: var(--main-border-color, rgba(50,50,50,.06));
+  margin: 12px 0 0;
+}
+
+.post-actions {
+  padding-bottom: 15px;
+  display: flex;
+  justify-content: center;
+  flex-wrap: wrap;
+  gap: 10px;
+}
+
+.post-actions .action {
+  min-width: 3.2em;
+  height: 3.2em;
+  border-radius: 100px;
+  border: 0;
+  background: var(--muted-bg-color, #f2f2f2);
+  color: var(--muted-color, #777);
+  display: inline-flex;
+  align-items: center;
+  justify-content: center;
+  gap: 4px;
+  padding: 0 14px;
+  cursor: pointer;
+  transition: .15s;
+}
+
+.post-actions .action:hover,
+.post-actions .action.is-active {
+  color: var(--focus-color, #f04494);
+  background: var(--focus-color-opacity1, rgba(240,68,148,.1));
+}
+
+.post-actions .action i {
+  font-size: 16px;
+}