fix(archives): 置顶文章不再把整月拽到顶部——置顶浮出分组流自成首节

用户实测：某月有一篇置顶时，该月全部文章跟着上浮。根因：sortPosts
置顶优先后，年/月分组按顺次建桶——置顶文章让所在月提前建桶到顶部。
修复：置顶文章单独渲染为分组流之前的一节（带徽标与计数），年/月分组
只对非置顶文章按自然时序建桶，月份各归各位。

验证: pnpm astro build exit 0；产物断言分组头顺序=置顶,2026-11,2026-04,2026-03,2026-02 且置顶文仅出现一次；E2E 61/61

Spec: none (用户实测报告的排序分组 bug 紧急修复)

Co-authored-by: GLM-5.3

src/components/PostList.astro

@@ -33,8 +33,13 @@ const TRACK_LABEL: Record<PostCategory, string> = {
 };
 const hrefOf = (id: string) => (locale === 'en' ? `/en/archives/${id}/` : `/archives/${id}/`);
 
+// 置顶浮出分组流（2026-11-05 用户实测修复）：置顶文章若留在分组流里，
+// 它所在月会因「顺次建桶」被提前建到顶部，整月文章跟着上浮——
+// 所以置顶单独一节渲染在年/月分组之前，分组只对非置顶文章按自然时序建桶。
+const pinned = visible.filter((p) => p.data.pinned);
+const flow = visible.filter((p) => !p.data.pinned);
 const byYear = new Map<number, CollectionEntry<'posts'>[]>();
-for (const post of visible) {
+for (const post of flow) {
   const year = post.data.pubDate.getUTCFullYear();
   const bucket = byYear.get(year);
   if (bucket) bucket.push(post);
@@ -107,6 +112,37 @@ const byMonth = (list: CollectionEntry<'posts'>[]) => {
   </div>
 ) : fold ? (
   <div class="post-list post-list-fold">
+    {pinned.length > 0 && (
+      <section class="month-block pinned-block">
+        <h3 class="month-head">
+          <span>{t('pinned_label', locale)}</span>
+          <span class="mono month-count">· {pinned.length} {units}</span>
+        </h3>
+        <ul>
+          {pinned.map((post) => (
+            <li>
+              <a class="row tap" href={hrefOf(post.id)}>
+                {post.data.category === 'reading' && (
+                  <i
+                    class="emo"
+                    style={`background:${post.data.mood ?? 'var(--mood)'}`}
+                    title="情绪色"
+                    aria-hidden="true"
+                  />
+                )}
+                <span class="row-title">{titleOverrides?.[post.id] ?? post.data.title}</span>
+                <span class="pin" title={t('pinned_label', locale)}>{t('pinned_label', locale)}</span>
+                {post.data.category !== 'reading' &&
+                  post.data.tags.map((tag) => <code class="tag">{`#${tag}`}</code>)}
+                <time class="row-date" datetime={post.data.pubDate.toISOString()}>
+                  {mmdd(post.data.pubDate)}
+                </time>
+              </a>
+            </li>
+          ))}
+        </ul>
+      </section>
+    )}
     {[...byYear.entries()].map(([year, list], i) => (
       <details class="year-fold" open={i === 0}>
         <summary class="year-summary">
@@ -153,6 +189,33 @@ const byMonth = (list: CollectionEntry<'posts'>[]) => {
   </div>
 ) : (
   <div class="post-list">
+    {pinned.length > 0 && (
+      <section class="year-block pinned-block" aria-label={t('pinned_label', locale)}>
+        <h2 class="year">{t('pinned_label', locale)}</h2>
+        <ul>
+          {pinned.map((post) => (
+            <li>
+              <a class="row tap" href={hrefOf(post.id)}>
+                {post.data.category === 'reading' && (
+                  <i
+                    class="emo"
+                    style={`background:${post.data.mood ?? 'var(--mood)'}`}
+                    title="情绪色"
+                    aria-hidden="true"
+                  />
+                )}
+                <span class="row-title">{titleOverrides?.[post.id] ?? post.data.title}</span>
+                {post.data.category !== 'reading' &&
+                  post.data.tags.map((tag) => <code class="tag">{`#${tag}`}</code>)}
+                <time class="row-date" datetime={post.data.pubDate.toISOString()}>
+                  {mmdd(post.data.pubDate)}
+                </time>
+              </a>
+            </li>
+          ))}
+        </ul>
+      </section>
+    )}
     {[...byYear.entries()].map(([year, list]) => (
       <section class="year-block" aria-label={`${year} 年文章`}>
         <h2 class="year">{year}</h2>
@@ -363,6 +426,8 @@ const byMonth = (list: CollectionEntry<'posts'>[]) => {
   .year-count { font-size: 12px; color: var(--ink-4); }
   .year-body { padding-bottom: var(--space-2); }
   .month-block + .month-block { margin-top: var(--space-3); }
+  /* 置顶节与第一个年折叠块之间的间隔 */
+  .pinned-block + .year-fold { margin-top: var(--space-4); }
   .month-head {
     display: flex;
     align-items: baseline;