feat: add setting to keep connection alive in background (#1196)

app/src/main/res/values-zh/strings.xml

@@ -128,6 +128,10 @@
     <string name="screen_files">文件</string>
     <string name="notif_title">Hermes</string>
     <string name="notif_waiting_replies">等待 Hermes 回复</string>
+    <string name="notif_connected_in_background">在后台保持连接</string>
+    <string name="notif_connecting">正在连接…</string>
+    <string name="notif_waiting_network">等待网络连接</string>
+    <string name="notif_reconnecting">正在重新连接</string>
     <string name="notif_new_message">新消息</string>
     <string name="notif_clarification_needed">Hermes 需要确认</string>
     <string name="notif_reply_placeholder">输入回复…</string>
@@ -177,6 +181,8 @@
     <string name="chat_camera_error">拍照失败</string>
     <string name="settings_sec_connection">连接</string>
     <string name="settings_field_token">认证令牌</string>
+    <string name="settings_keep_connected_in_background_title">在后台保持连接</string>
+    <string name="settings_keep_connected_in_background_desc">在使用其他应用时保持 Hermes 连接。会显示常驻通知，并可能消耗更多电量。</string>
     <string name="settings_sec_behavior">行为</string>
     <string name="settings_item_auto_reconnect">自动重连</string>
     <string name="settings_desc_auto_reconnect">断开后自动重新连接</string>