Add multi-server 3x-ui registry with per-panel subscription URLs.

Admins can manage several 3x-ui panels by name and select which one issues invite/user configs via that server's /sub base URL.

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

translations/zh.json

@@ -300,6 +300,16 @@
   "xui_inbound_label": "VLESS 入站",
   "xui_inbound_auto": "自动（第一个 VLESS 入站）",
   "xui_inbound_hint": "创建 3x-ui VLESS 配置时使用。请先在 3x-ui 中创建 VLESS 入站。",
+  "xui_servers_title": "3x-ui 服务器",
+  "xui_servers_hint": "可添加多个 3x-ui 面板。创建配置时按名称选择服务器，并使用其订阅基础 URL。",
+  "xui_servers_empty": "暂无 3x-ui 服务器。请点击添加。",
+  "xui_servers_manage_hint": "面板与订阅地址在下方「3x-ui 服务器」中管理。",
+  "xui_server_add": "添加服务器",
+  "xui_server_name_label": "名称 / 描述",
+  "xui_server_name_hint": "显示在邀请与用户表单中（如 US、NL）。",
+  "xui_server_select_label": "3x-ui 服务器",
+  "xui_server_select_hint": "选择签发订阅 URL 的 3x-ui 面板。",
+  "xui_server_delete_confirm": "从面板删除此 3x-ui 服务器？",
   "sync_now_btn": "🔄 立即同步",
   "delete_sync_btn": "🗑 删除同步数据",
   "auto_create_conns": "自动创建连接",