fix(homepage): force-visible post stream against Bootstrap fade

Remove Bootstrap fade/in classes from the active home pane, render cards
as <article class="posts-item">, and lock list opacity/display with
!important so published posts cannot stay invisible.

assets/css/frontend/post-card.css

@@ -25,9 +25,13 @@
 /* ============================================================
  * 通用 posts-item 基础 — 对齐 zibll line 7585
  * ============================================================ */
+posts.posts-item,
+article.posts-item,
 .posts-item {
     /* Custom element <posts> is inline by default — force block layout. */
-    display: block;
+    display: block !important;
+    opacity: 1 !important;
+    visibility: visible !important;
     padding: 20px;
     margin: 15px 0;
     background: var(--main-bg-color, var(--surface-1, #fff));