feat(settings): schedule picker, toggle placement, sub-theme docs link

- Replace the Telegram "Notification Time" free-text field with a guided
  cron builder: @every + number + unit (s/m/h), the @hourly/@daily/@weekly/
  @monthly macros, and a Custom option that seeds a valid 6-field crontab
  (cron runs with seconds enabled) as an escape hatch.
- Move "Restart Xray After Auto Disable" from the External Traffic tab to
  Panel Settings, where it belongs.
- Add a "Template guide" link to the Sub Theme Directory setting pointing at
  docs/custom-subscription-templates.md.
- Localize all new strings across every locale.

internal/web/translation/zh-CN.json

@@ -1005,7 +1005,18 @@
       "telegramChatId": "管理员聊天 ID",
       "telegramChatIdDesc": "Telegram 管理员聊天 ID (多个以逗号分隔)（可通过 {'@'}userinfobot 获取，或在机器人中使用 '/id' 命令获取）",
       "telegramNotifyTime": "通知时间",
-      "telegramNotifyTimeDesc": "设置周期性的 Telegram 机器人通知时间（使用 crontab 时间格式）",
+      "telegramNotifyTimeDesc": "Telegram 机器人发送周期性报告的频率。选择预设间隔，或选择“自定义”以输入 crontab 表达式。",
+      "notifyTime": {
+        "every": "@every — 按间隔重复",
+        "hourly": "@hourly — 每小时",
+        "daily": "@daily — 每天 00:00",
+        "weekly": "@weekly — 每周",
+        "monthly": "@monthly — 每月",
+        "custom": "自定义 (crontab)",
+        "seconds": "秒",
+        "minutes": "分钟",
+        "hours": "小时"
+      },
       "tgNotifyBackup": "数据库备份",
       "tgNotifyBackupDesc": "发送带有报告的数据库备份文件",
       "tgNotifyLogin": "登录通知",
@@ -1036,6 +1047,7 @@
       "subAnnounceDesc": "VPN 客户端中显示的公告文本",
       "subThemeDir": "订阅主题目录",
       "subThemeDirDesc": "包含自定义订阅页面模板 (index.html/sub.html) 的文件夹的绝对路径（例如 /etc/3x-ui/sub_templates/my-theme/）。留空则使用默认页面。",
+      "subThemeDirDocs": "模板指南 ↗",
       "subEnableRouting": "启用路由",
       "subEnableRoutingDesc": "在 VPN 客户端中启用路由的全局设置。（僅限 Happ）",
       "subRoutingRules": "路由規則",