feat: 外观支持自定义 CSS/JS，并升级发帖工作台与积分存量看板

后台可注入全站 CSS/JS（SSR 生效，CSS 可热换）；发帖/编辑改为锁一屏工作室；经济看板增加存量健康度；主题令牌与弹层误关一并收紧。

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

frontend/components/PostRow.tsx

@@ -45,7 +45,7 @@ export default async function PostRow({
 
   return (
     <div
-      className={`group relative flex items-center px-4 sm:px-5 border-t cursor-pointer transition-colors hover:bg-[var(--accent-soft)] focus-within:bg-[var(--accent-soft)] j13-fade-up ${
+      className={`group relative flex items-center px-4 sm:px-5 border-t cursor-pointer transition-colors hover:bg-[var(--panel-2)] focus-within:bg-[var(--panel-2)] j13-fade-up ${
         compact ? "gap-2.5 sm:gap-3" : "gap-3.5 sm:gap-4"
       }`}
       style={{