feat(leader): Leader 管理展示跟单/回测数量并支持跳转筛选

- 后端：LeaderDto 增加 backtestCount，LeaderService 统计回测数并返回
- Leader 列表：展示跟单数、回测数，点击跳转跟单配置/回测页并带 leaderId 筛选
- 跟单配置页：从 URL 读取 leaderId 并应用筛选，Leader 下拉改用 LeaderSelect
- 回测页：支持 Leader 筛选，页面加载时请求 Leader 列表，筛选与详情统一显示规则
- LeaderSelect：支持 style，回测/跟单筛选统一使用
- 多语言：补充 leaderList 相关 key
- 移动端：Leader 管理卡片内按钮增加内边距 padding 8px 16px

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

frontend/src/components/LeaderSelect.tsx

@@ -14,6 +14,7 @@ interface LeaderSelectProps {
   showSearch?: boolean
   allowClear?: boolean
   notFoundContent?: React.ReactNode
+  style?: React.CSSProperties
 }
 
 const LeaderSelect: React.FC<LeaderSelectProps> = ({
@@ -25,7 +26,8 @@ const LeaderSelect: React.FC<LeaderSelectProps> = ({
   disabled,
   showSearch = true,
   allowClear = false,
-  notFoundContent
+  notFoundContent,
+  style
 }) => {
   // 处理选择变化
   const handleChange = (val: number | undefined) => {
@@ -46,6 +48,7 @@ const LeaderSelect: React.FC<LeaderSelectProps> = ({
       showSearch={showSearch}
       allowClear={allowClear}
       notFoundContent={notFoundContent}
+      style={style}
       optionFilterProp="label"
       optionLabelProp="label"
     >