feat: 类型帖互动、积分经济与发帖体验

补齐问答采纳/重开、投票匿名与有票禁编、悬赏过期退回、抽奖回帖开奖，并接入积分账本与发帖附件可见性。

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

frontend/components/ContentLockGate.tsx

@@ -0,0 +1,92 @@
+"use client";
+
+import { useState } from "react";
+import { useRouter } from "next/navigation";
+import Link from "next/link";
+import { Lock } from "lucide-react";
+import { apiUnlockPost } from "@/lib/api";
+import { toast } from "@/lib/toast";
+
+export default function ContentLockGate({
+  postId,
+  hint,
+  access,
+  points,
+  loggedIn,
+}: {
+  postId: number;
+  hint?: string;
+  access?: string;
+  points?: number;
+  loggedIn: boolean;
+}) {
+  const router = useRouter();
+  const [busy, setBusy] = useState(false);
+
+  const unlock = async () => {
+    setBusy(true);
+    try {
+      const res = await apiUnlockPost(String(postId));
+      if (res.post) {
+        toast("已解锁全文", "ok");
+        router.refresh();
+      } else {
+        toast(res.error || "解锁失败", "error");
+      }
+    } catch {
+      toast("解锁失败", "error");
+    } finally {
+      setBusy(false);
+    }
+  };
+
+  return (
+    <div
+      className="rounded-[14px] px-6 py-10 text-center my-4"
+      style={{
+        background: "var(--accent-soft)",
+        border: "1px solid color-mix(in srgb, var(--accent) 20%, transparent)",
+      }}
+    >
+      <Lock size={28} className="mx-auto mb-3" style={{ color: "var(--accent)" }} />
+      <p className="font-bold text-[16px] mb-1" style={{ color: "var(--ink)" }}>
+        {hint || "正文暂不可见"}
+      </p>
+      <p className="meta text-[13px] mb-5">
+        {access === "points"
+          ? `支付 ${points || 0} 积分后可阅读全文`
+          : access === "reply"
+            ? "发表一条回复后即可阅读全文"
+            : access === "login"
+              ? "登录后即可阅读全文"
+              : null}
+      </p>
+      {access === "login" && !loggedIn && (
+        <Link
+          href={`/login?redirect=${encodeURIComponent(`/post/${postId}`)}`}
+          className="btn btn-primary"
+        >
+          去登录
+        </Link>
+      )}
+      {access === "points" && loggedIn && (
+        <button type="button" className="btn btn-primary" disabled={busy} onClick={() => void unlock()}>
+          {busy ? "解锁中…" : `支付 ${points || 0} 积分解锁`}
+        </button>
+      )}
+      {access === "points" && !loggedIn && (
+        <Link
+          href={`/login?redirect=${encodeURIComponent(`/post/${postId}`)}`}
+          className="btn btn-primary"
+        >
+          登录后解锁
+        </Link>
+      )}
+      {access === "reply" && (
+        <a href="#comments" className="btn btn-primary">
+          去回复
+        </a>
+      )}
+    </div>
+  );
+}