feat: 帖子收藏与用户关注

- 新增收藏功能：favorite 服务与 handler、FavoriteButton 组件
- 新增关注功能：follow 服务与 handler、FollowButton 组件
- 用户主页适配关注/粉丝与收藏展示
- flash 消息工具、广告与侧边栏组件微调

frontend/app/admin/content/ContentAdmin.tsx

@@ -689,7 +689,7 @@ export default function ContentAdmin({
                     c.post_title
                   ) : (
                     <Link
-                      href={`/post/${c.post_id}`}
+                      href={`/post/${c.post_id}#comment-${c.id}`}
                       className="hover:underline"
                       style={{ color: "var(--accent)" }}
                     >

frontend/app/admin/users/UsersAdmin.tsx

@@ -3,6 +3,7 @@
 import { useCallback, useEffect, useMemo, useRef, useState } from "react";
 import { useRouter } from "next/navigation";
 import Link from "next/link";
+import { boardColor } from "@/components/BoardIcon";
 import {
   ArrowUpDown,
   ChevronDown,
@@ -352,6 +353,12 @@ export default function UsersAdmin({
     return m;
   }, [boards]);
 
+  const boardColorMap = useMemo(() => {
+    const m = new Map<number, number>();
+    boards.forEach((b) => m.set(b.id, boardColor(b)));
+    return m;
+  }, [boards]);
+
   useEffect(() => {
     apiListBoards()
       .then((r) => setBoards(r.boards ?? []))
@@ -755,7 +762,7 @@ export default function UsersAdmin({
       case "role":
         return (
           <div className="min-w-0">
-            <RoleBadge role={u.role} boardIds={u.board_ids} boardNames={boardNameMap} truncate />
+            <RoleBadge role={u.role} boardIds={u.board_ids} boardNames={boardNameMap} boardColors={boardColorMap} truncate />
           </div>
         );
       case "status":
@@ -945,7 +952,7 @@ export default function UsersAdmin({
                             {u.nickname}
                           </span>
                           {u.role !== ROLES.USER && (
-                            <RoleBadge role={u.role} boardIds={u.board_ids} boardNames={boardNameMap} />
+                            <RoleBadge role={u.role} boardIds={u.board_ids} boardNames={boardNameMap} boardColors={boardColorMap} />
                           )}
                           {isSelf && (
                             <span

frontend/app/admin/users/[id]/UserAuditClient.tsx

@@ -353,7 +353,7 @@ export default function UserAuditClient({
                       <span className="text-[11.5px] meta">帖子 #{c.post_id}</span>
                     ) : (
                       <Link
-                        href={`/post/${c.post_id}`}
+                        href={`/post/${c.post_id}#comment-${c.id}`}
                         className="text-[11.5px] hover:underline"
                         style={{ color: "var(--accent)" }}
                       >