feat(posts): 类型特殊块移至正文下，采纳答案卡与中奖楼层按评论标记

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

frontend/components/AcceptedAnswerCard.tsx

@@ -0,0 +1,86 @@
+import Link from "next/link";
+import { CheckCircle2 } from "lucide-react";
+import type { AcceptedAnswer } from "@/lib/api";
+import Avatar from "@/components/Avatar";
+import MarkdownBody from "@/components/MarkdownBody";
+import AcceptedAnswerReopen from "@/components/AcceptedAnswerReopen";
+
+/** 正文下方的已采纳答案卡：头像 + 昵称 + 全文；问答已解决时并入状态与「重新打开」 */
+export default async function AcceptedAnswerCard({
+  answer,
+  variant = "question",
+  postId,
+  canReopen = false,
+}: {
+  answer: AcceptedAnswer;
+  /** 问答用「最佳答案」，悬赏用「已采纳」 */
+  variant?: "question" | "bounty";
+  postId?: number;
+  canReopen?: boolean;
+}) {
+  const name = answer.user.nickname || answer.user.username || "用户";
+  const label = variant === "bounty" ? "已采纳" : "最佳答案";
+  const showReopen = variant === "question" && canReopen && !!postId;
+
+  return (
+    <section className="j13-accepted-answer" aria-label={variant === "question" ? "问答 · 已解决" : label}>
+      <header className="j13-accepted-answer__head">
+        <div className="j13-accepted-answer__meta min-w-0">
+          {variant === "question" && (
+            <p className="j13-accepted-answer__status">问答 · 已解决</p>
+          )}
+          <div className="j13-accepted-answer__author min-w-0">
+            <span className="badge-accepted shrink-0">
+              <CheckCircle2 size={13} aria-hidden />
+              {label}
+            </span>
+            <Link
+              href={`/u/${answer.user.id}`}
+              className="shrink-0"
+              aria-label={name}
+            >
+              <Avatar name={name} src={answer.user.avatar || undefined} size={36} />
+            </Link>
+            <div className="min-w-0 flex flex-col gap-0.5">
+              <Link
+                href={`/u/${answer.user.id}`}
+                className="truncate text-[14px] font-semibold hover:text-[var(--accent)] transition-colors"
+                style={{ color: "var(--ink)" }}
+              >
+                {name}
+              </Link>
+              <p className="meta text-[12px] flex items-center gap-1.5 flex-wrap">
+                <time dateTime={answer.created_at}>
+                  {new Date(answer.created_at).toLocaleString("zh-CN")}
+                </time>
+                {answer.floor > 0 && (
+                  <>
+                    <span aria-hidden>·</span>
+                    <a
+                      href={`#comment-${answer.id}`}
+                      className="hover:underline"
+                      style={{ color: "var(--accent)" }}
+                    >
+                      #{answer.floor}
+                    </a>
+                  </>
+                )}
+              </p>
+            </div>
+          </div>
+        </div>
+        {showReopen && <AcceptedAnswerReopen postId={postId!} />}
+      </header>
+
+      <div className="j13-accepted-answer__body">
+        {answer.deleted ? (
+          <p className="meta text-[14px]" style={{ color: "var(--ink-3)" }}>
+            该答案已被删除
+          </p>
+        ) : (
+          <MarkdownBody content={answer.content} className="prose-content prose-comment" />
+        )}
+      </div>
+    </section>
+  );
+}