feat: 帖子分级置顶（板块/全站）与板块管理员置顶权限、消息管理权限调整

frontend/app/admin/pinned/page.tsx

@@ -0,0 +1,42 @@
+import type { Metadata } from "next";
+import { cookies } from "next/headers";
+import { authCookieHeader } from "@/lib/cookies";
+import { fetchBoards, type BoardWithCount } from "@/lib/api";
+import { getMeCached } from "@/lib/serverData";
+import { canModerateAny, isAdminOrAbove } from "@/lib/roles";
+import Forbidden from "../Forbidden";
+import PinnedAdmin from "./PinnedAdmin";
+
+export const metadata: Metadata = {
+  title: "置顶管理",
+};
+
+export default async function AdminPinnedPage() {
+  const cookie = authCookieHeader(await cookies());
+  const me = await getMeCached(cookie || undefined);
+
+  // 管理员及以上排全站置顶；板块管理员排自己授权板块的板块置顶
+  if (!me.user || !canModerateAny(me.user)) {
+    return <Forbidden text="你所在的角色没有置顶管理权限，或尚未被授权任何板块。" />;
+  }
+
+  // 板块管理员只能看到自己被授权的板块
+  let boards: BoardWithCount[] = [];
+  try {
+    const r = await fetchBoards();
+    boards = r.boards ?? [];
+  } catch {
+    boards = [];
+  }
+  if (!isAdminOrAbove(me.user.role)) {
+    const ids = new Set(me.user.board_ids ?? []);
+    boards = boards.filter((b) => ids.has(b.id));
+  }
+
+  return (
+    <PinnedAdmin
+      boards={boards.map((b) => ({ id: b.id, name: b.name }))}
+      canGlobal={isAdminOrAbove(me.user.role)}
+    />
+  );
+}