fix(client): reword the heat card subtitle

src/client/i18n.ts

@@ -253,7 +253,7 @@ export const DICT_ZH: Record<string, string> = {
   'ov.kpi.costSub': 'models.dev 刊例价估算',
   'ov.kpi.cacheSub': '缓存读取 / 计费输入',
   'ov.heat.title': '活跃度',
-  'ov.heat.sub': '点击可筛选会话',
+  'ov.heat.sub': '点击按日期筛选',
   'ov.heat.empty': '暂无活跃数据 — 会话产生模型请求后，这里会显示每日用量',
   'ov.heat.sessions': '{n} 个活跃会话',
   'ov.heat.wd.1': '一', 'ov.heat.wd.3': '三', 'ov.heat.wd.5': '五',
@@ -527,7 +527,7 @@ export const DICT_EN: Record<string, string> = {
   'ov.kpi.costSub': 'estimated at models.dev list prices',
   'ov.kpi.cacheSub': 'cache reads of billed input',
   'ov.heat.title': 'Activity',
-  'ov.heat.sub': 'Click a day to filter sessions',
+  'ov.heat.sub': 'Click to filter by day',
   'ov.heat.empty': 'No activity yet — daily usage appears once sessions make model requests',
   'ov.heat.sessions': '{n} active sessions',
   'ov.heat.wd.1': 'M', 'ov.heat.wd.3': 'W', 'ov.heat.wd.5': 'F',