fix(widgets): restore hot-posts rank badge position per reference

Remove unscoped .img-badge top/left overrides from post-card.css and its
build aggregates that hijacked the reference-parity rules in main.css
(top:.6em / .hot-posts left:-15px). Also drop dead .widget-hot-posts
legacy blocks with no remaining markup references.

assets/css/frontend/sidebar.css

@@ -94,41 +94,6 @@
   border-bottom: none;
 }
 
-/* 热门文章 widget */
-.widget-hot-posts .hot-post-item {
-  display: flex;
-  gap: 10px;
-  padding: 8px 0;
-  border-bottom: 1px solid var(--color-line-soft, rgba(0, 0, 0, 0.03));
-}
-
-.widget-hot-posts .hot-post-item:last-child {
-  border-bottom: none;
-}
-
-.widget-hot-posts .hot-post-item__thumb {
-  width: 60px;
-  height: 45px;
-  border-radius: 4px;
-  object-fit: cover;
-  flex-shrink: 0;
-}
-
-.widget-hot-posts .hot-post-item__title {
-  font-size: 13px;
-  color: var(--color-ink, #333);
-  display: -webkit-box;
-  -webkit-line-clamp: 2;
-  -webkit-box-orient: vertical;
-  overflow: hidden;
-}
-
-.widget-hot-posts .hot-post-item__meta {
-  font-size: 11px;
-  color: var(--color-ink-4, #999);
-  margin-top: 2px;
-}
-
 /* 侧边栏响应式 — width/float 由 layout.css 的 --sidebar-width + site-layout-* 拥有。
  * 禁止在这里硬编码 280px（会与 content-layout gutter 失配导致叠层/空隙）。 */
 @media (max-width: 991px) {