polish(frontend): 加大聊天侧栏群名，并强化帖子页作者卡

作者卡补充签名、积分与连签；聊天会话标题字号调至 15px。

Co-authored-by: Cursor <cursoragent@cursor.com>

frontend/app/chat/ChatShell.tsx

@@ -468,7 +468,7 @@ export default function ChatShell({
                       <div className="flex-1 min-w-0">
                         <div className="flex items-center gap-1.5">
                           <span
-                            className="text-[13.5px] truncate"
+                            className="text-[15px] truncate"
                             style={{ color: "var(--ink)" }}
                           >
                             {roomTitle(room)}

frontend/app/post/[id]/page.tsx

@@ -88,11 +88,6 @@ function extractToc(content: string): TocItem[] {
   return items;
 }
 
-function formatYearMonth(dateStr: string) {
-  const d = new Date(dateStr);
-  return `${d.getFullYear()}.${String(d.getMonth() + 1).padStart(2, "0")}`;
-}
-
 function formatYMD(dateStr: string) {
   const d = new Date(dateStr);
   return `${d.getFullYear()}.${String(d.getMonth() + 1).padStart(2, "0")}.${String(
@@ -151,6 +146,13 @@ function BoardCard({ board }: { board: Board }) {
 
 function AuthorRailCard({ profile }: { profile: UserProfile }) {
   const u = profile.user;
+  const signature = (u.signature || "").trim();
+  const { post_count, comment_count, points, streak } = profile.stats;
+  const stats = [
+    { label: "发帖", value: post_count },
+    { label: "评论", value: comment_count },
+    { label: "积分", value: points },
+  ];
   return (
     <section className="j13-module shrink-0" aria-labelledby="author-card-title">
       <p className="j13-module-title mb-3" id="author-card-title">
@@ -168,21 +170,55 @@ function AuthorRailCard({ profile }: { profile: UserProfile }) {
           >
             {u.nickname}
           </Link>
-          {u.role !== "user" && <RoleBadge role={u.role} boardIds={u.board_ids} />}
+          <p className="meta mt-0.5 truncate">@{u.username}</p>
+          {u.role !== "user" && (
+            <div className="mt-1">
+              <RoleBadge role={u.role} boardIds={u.board_ids} />
+            </div>
+          )}
         </div>
       </div>
-      <p className="meta mt-3">{formatYearMonth(u.created_at)} 加入</p>
-      <div className="grid grid-cols-2 gap-2 mt-2.5">
-        <div className="j13-stat">
-          <span className="j13-stat-num">{profile.stats.post_count}</span>
-          <span className="j13-stat-lab">发帖</span>
-        </div>
-        <div className="j13-stat">
-          <span className="j13-stat-num">{profile.stats.comment_count}</span>
-          <span className="j13-stat-lab">评论</span>
-        </div>
+      {/* 有签名则展示；无则留空，不放占位文案 */}
+      {signature ? (
+        <p
+          className="mt-3 text-[12.5px] leading-relaxed line-clamp-3"
+          style={{ color: "var(--ink-2)" }}
+          title={signature}
+        >
+          {signature}
+        </p>
+      ) : null}
+      <div
+        className="mt-3 grid grid-cols-3 border-t"
+        style={{ borderColor: "var(--line)" }}
+      >
+        {stats.map((s, i) => (
+          <div
+            key={s.label}
+            className="px-1.5 py-2.5 text-center"
+            style={i > 0 ? { borderLeft: "1px solid var(--line)" } : undefined}
+          >
+            <p
+              className="text-[17px] font-semibold leading-none tabular-nums"
+              style={{ color: "var(--ink)" }}
+            >
+              {s.value}
+            </p>
+            <p className="mt-1.5 text-[11px]" style={{ color: "var(--ink-3)" }}>
+              {s.label}
+            </p>
+          </div>
+        ))}
       </div>
-      <Link href={`/u/${u.id}`} className="btn btn-line btn-sm w-full justify-center mt-3.5">
+      {streak > 0 && (
+        <p
+          className="mt-2 flex items-center justify-center gap-1 text-[11.5px] font-medium"
+          style={{ color: "var(--gold)" }}
+        >
+          <Flame size={11.5} /> 连签 {streak} 天
+        </p>
+      )}
+      <Link href={`/u/${u.id}`} className="btn btn-line btn-sm w-full justify-center mt-3">
         访问主页
       </Link>
     </section>
@@ -278,6 +314,9 @@ function RelatedPosts({
 
 /* 移动端 / 窄屏作者卡（xl 以下内联在正文与评论之间，替代左栏作者模块） */
 function AuthorCardStacked({ profile }: { profile: UserProfile }) {
+  const u = profile.user;
+  const signature = (u.signature || "").trim();
+  const { post_count, comment_count, points, streak } = profile.stats;
   return (
     <div className="panel p-5 sm:p-6">
       <p
@@ -286,29 +325,45 @@ function AuthorCardStacked({ profile }: { profile: UserProfile }) {
       >
         关于作者
       </p>
-      <div className="flex items-center gap-4 flex-wrap">
-        <Link href={`/u/${profile.user.id}`} className="shrink-0" aria-label={profile.user.nickname}>
-          <Avatar name={profile.user.nickname || profile.user.username} src={profile.user.avatar || undefined} size={52} />
+      <div className="flex items-start gap-4 flex-wrap">
+        <Link href={`/u/${u.id}`} className="shrink-0" aria-label={u.nickname}>
+          <Avatar name={u.nickname || u.username} src={u.avatar || undefined} size={52} />
         </Link>
         <div className="min-w-0 flex-1">
           <div className="flex items-center gap-2 flex-wrap">
             <Link
-              href={`/u/${profile.user.id}`}
+              href={`/u/${u.id}`}
               className="font-semibold text-[15px] hover:text-[var(--accent)] transition-colors"
               style={{ color: "var(--ink)" }}
             >
-              {profile.user.nickname}
+              {u.nickname}
             </Link>
-            {profile.user.role !== "user" && (
-              <RoleBadge role={profile.user.role} boardIds={profile.user.board_ids} />
-            )}
+            {u.role !== "user" && <RoleBadge role={u.role} boardIds={u.board_ids} />}
           </div>
-          <p className="meta mt-1">
-            {formatYearMonth(profile.user.created_at)} 加入 · 发帖 {profile.stats.post_count} · 评论{" "}
-            {profile.stats.comment_count}
+          <p className="meta mt-1 flex items-center gap-1.5 flex-wrap">
+            <span>@{u.username}</span>
+            <span aria-hidden>·</span>
+            <span>发帖 {post_count}</span>
+            <span aria-hidden>·</span>
+            <span>评论 {comment_count}</span>
+            <span aria-hidden>·</span>
+            <span>积分 {points}</span>
+            {streak > 0 && (
+              <>
+                <span aria-hidden>·</span>
+                <span className="inline-flex items-center gap-0.5 font-medium" style={{ color: "var(--gold)" }}>
+                  <Flame size={11} /> 连签 {streak} 天
+                </span>
+              </>
+            )}
           </p>
+          {signature ? (
+            <p className="mt-2 text-[13px] leading-relaxed line-clamp-2" style={{ color: "var(--ink-2)" }}>
+              {signature}
+            </p>
+          ) : null}
         </div>
-        <Link href={`/u/${profile.user.id}`} className="btn btn-line btn-sm shrink-0">
+        <Link href={`/u/${u.id}`} className="btn btn-line btn-sm shrink-0 self-center">
           访问主页
         </Link>
       </div>