feat: 全站评论开关，并统一后台表单控件

关闭评论后前台隐藏评论能力；外观/设置/公告改用 AdminField 与 Stepper。

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

frontend/app/page.tsx

@@ -10,7 +10,7 @@ import {
   type BoardSidebarResponse,
 } from "@/lib/api";
 import { authCookieHeader } from "@/lib/cookies";
-import { getMeCached } from "@/lib/serverData";
+import { getMeCached, getPublicSettingsCached } from "@/lib/serverData";
 import Pagination from "@/components/Pagination";
 import PostRow from "@/components/PostRow";
 import FeedTabs, { type FeedSort } from "@/components/home/FeedTabs";
@@ -32,8 +32,11 @@ interface HomePageProps {
   searchParams: Promise<{ q?: string; page?: string; sort?: string; board?: string }>;
 }
 
-function normalizeSort(v?: string): FeedSort {
-  if (v === "new" || v === "recommended") return v;
+function normalizeSort(v: string | undefined, allowComments: boolean): FeedSort {
+  if (v === "recommended") return "recommended";
+  if (v === "new") return "new";
+  if (!allowComments) return "new";
+  if (v === "latest") return "latest";
   return "latest";
 }
 
@@ -75,11 +78,12 @@ export default async function HomePage({ searchParams }: HomePageProps) {
   const sp = await searchParams;
   const keyword = sp.q?.trim() || "";
   const page = Math.max(1, parseInt(sp.page || "1", 10) || 1);
-  const sort = normalizeSort(sp.sort);
   const boardId = Math.max(0, parseInt(sp.board || "0", 10) || 0);
   const isSearch = keyword.length > 0;
 
   const cookie = authCookieHeader(await cookies());
+  const allowComments = (await getPublicSettingsCached()).allow_comments !== false;
+  const sort = normalizeSort(sp.sort, allowComments);
   // 与 layout 共享同一份 /me 请求（React cache 去重）
   const mePromise = getMeCached(cookie || undefined);
   const postsPromise = fetchPosts(
@@ -216,6 +220,7 @@ export default async function HomePage({ searchParams }: HomePageProps) {
               hot={boardSidebar.hot}
               activeUsers={boardSidebar.active_users}
               checkin={boardSidebar.checkin ?? undefined}
+              allowComments={allowComments}
             />
           ) : boardPanelsMissing ? (
             <BoardMissingPanel />
@@ -229,6 +234,7 @@ export default async function HomePage({ searchParams }: HomePageProps) {
               announcements={overview.announcements}
               newUsers={overview.new_users}
               checkin={overview.checkin ?? undefined}
+              allowComments={allowComments}
             />
           )
         )}
@@ -245,6 +251,7 @@ export default async function HomePage({ searchParams }: HomePageProps) {
               hot={boardSidebar.hot}
               activeUsers={boardSidebar.active_users}
               checkin={boardSidebar.checkin ?? undefined}
+              allowComments={allowComments}
             />
           </div>
         ) : null
@@ -258,6 +265,7 @@ export default async function HomePage({ searchParams }: HomePageProps) {
               announcements={overview.announcements}
               newUsers={overview.new_users}
               checkin={overview.checkin ?? undefined}
+              allowComments={allowComments}
             />
           </div>
         )