add FOREGROUND_SERVICE for no_tun mode, not using vpn service (#1203)

1. add FOREGROUND_SERVICE related code, connection not to be **blocked by android system** when apps running in background
2. no_tun mode not enabling vpnservice, makeing other app to use vpnservice

Co-authored-by: Copilot <175728472+Copilot@users.noreply.github.com>

easytier-gui/src-tauri/gen/android/app/src/main/AndroidManifest.xml

@@ -1,6 +1,10 @@
 <?xml version="1.0" encoding="utf-8"?>
 <manifest xmlns:android="http://schemas.android.com/apk/res/android">
     <uses-permission android:name="android.permission.INTERNET" />
+    <uses-permission android:name="android.permission.FOREGROUND_SERVICE" />
+    <uses-permission android:name="android.permission.POST_NOTIFICATIONS" />
+    <uses-permission android:name="android.permission.FOREGROUND_SERVICE_DATA_SYNC" />
+
     <application
         android:icon="@mipmap/ic_launcher"
         android:label="@string/app_name"
@@ -18,6 +22,12 @@
                 <category android:name="android.intent.category.LAUNCHER" />
             </intent-filter>
         </activity>
+        <service
+            android:name=".MainForegroundService"
+            android:foregroundServiceType="dataSync"
+            android:enabled="true"
+            android:exported="false">
+        </service>
 
         <provider
           android:name="androidx.core.content.FileProvider"

easytier-gui/src-tauri/gen/android/app/src/main/java/com/kkrainbow/easytier/MainActivity.kt

@@ -1,3 +1,20 @@
 package com.kkrainbow.easytier
 
-class MainActivity : TauriActivity()
+import android.content.Intent
+import android.os.Build
+import android.os.Bundle
+class MainActivity : TauriActivity() {
+    override fun onCreate(savedInstanceState: Bundle?) {
+        super.onCreate(savedInstanceState)
+        initService()
+    }
+
+    private fun initService() {
+        val serviceIntent = Intent(this, MainForegroundService::class.java)
+        if (Build.VERSION.SDK_INT >= Build.VERSION_CODES.O) {
+            startForegroundService(serviceIntent)
+        } else {
+            startService(serviceIntent)
+        }
+    }
+}

easytier-gui/src-tauri/gen/android/app/src/main/java/com/kkrainbow/easytier/MainForegroundService.kt

@@ -0,0 +1,64 @@
+package com.kkrainbow.easytier
+import android.app.Notification
+import android.app.NotificationChannel
+import android.app.NotificationManager
+import android.app.Service
+import android.content.Intent
+import android.content.pm.ServiceInfo
+import android.os.Build
+import android.os.IBinder
+import androidx.core.app.NotificationCompat
+import android.util.Log
+
+class MainForegroundService : Service() {
+    companion object {
+        const val CHANNEL_ID = "easytier_channel"
+        const val NOTIFICATION_ID = 1355
+        // You can add more constants if needed
+    }
+
+    override fun onCreate() {
+        super.onCreate()
+    }
+
+    override fun onStartCommand(intent: Intent?, flags: Int, startId: Int): Int {
+        createNotificationChannel()
+        val notification = NotificationCompat.Builder(this, CHANNEL_ID)
+            .setContentTitle("easytier Running")
+            .setContentText("easytier is available on localhost")
+            .setSmallIcon(android.R.drawable.ic_menu_manage)
+            .build()
+       if (Build.VERSION.SDK_INT >= Build.VERSION_CODES.Q) {
+            startForeground(
+                NOTIFICATION_ID,
+                notification,
+                ServiceInfo.FOREGROUND_SERVICE_TYPE_DATA_SYNC
+            )
+        } else {
+            startForeground(NOTIFICATION_ID, notification)
+        }
+        return START_STICKY
+    }
+
+    override fun onDestroy() {
+        super.onDestroy()
+    }
+
+    override fun onBind(intent: Intent?): IBinder? = null
+
+    private fun createNotificationChannel() {
+        if (Build.VERSION.SDK_INT >= Build.VERSION_CODES.O) {
+          try {
+            val channel = NotificationChannel(
+                CHANNEL_ID,
+                "easytier notice",
+                NotificationManager.IMPORTANCE_DEFAULT
+            )
+            val manager = getSystemService(NotificationManager::class.java)
+            manager?.createNotificationChannel(channel)
+            } catch (e: Exception) {
+                Log.e("MainForegroundService", "Failed to create notification channel", e)
+            }
+        }
+    }
+}