Người quan sát Bluetooth

In Android 13 and higher, Bluetooth has to be turned on by pulling down the notification bar, so a notification text was added. I removed the foreground service and made it run only when the app is turned on.
The build version of the app was changed to Android 14, and the development tools and all libraries were changed from versions from 2 years ago to the latest stable version. The minimum specifications of the app were increased from Android 4.1 to Android 6.0 or higher.