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/app/admin/AdminNav.tsx

@@ -12,6 +12,7 @@ import {
   ShieldCheck,
   ArrowLeft,
   ClipboardCheck,
+  Coins,
 } from "lucide-react";
 import type { User } from "@/lib/api";
 import { apiAdminPendingCounts } from "@/lib/api";
@@ -47,6 +48,12 @@ const NAV_ITEMS: NavItem[] = [
     visible: (u) => canModerateAny(u),
     pendingBadge: true,
   },
+  {
+    href: "/admin/economy",
+    label: "积分看板",
+    icon: Coins,
+    visible: (u) => isAdminOrAbove(u.role),
+  },
   {
     href: "/admin/announcements",
     label: "公告管理",