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/Header.tsx

@@ -281,6 +281,7 @@ export default function Header({
             className={`${iconBtn} hidden lg:inline-flex`}
             style={iconBtnStyle}
             aria-label="切换主题"
+            data-tip={theme === "dark" ? "切换浅色" : "切换深色"}
           >
             {theme === "dark" ? <Sun size={17} /> : <Moon size={17} />}
           </button>
@@ -289,6 +290,7 @@ export default function Header({
               href="/chat"
               prefetch={false}
               aria-label="消息"
+              data-tip="消息"
               className="relative inline-flex items-center justify-center w-10 h-10 rounded-full transition-colors"
               style={{
                 color: pathname?.startsWith("/chat")