feat: 新增站内消息系统，支持通知与订单跳转

android/app/build.gradle.kts

@@ -13,6 +13,8 @@ android {
     compileOptions {
         sourceCompatibility = JavaVersion.VERSION_17
         targetCompatibility = JavaVersion.VERSION_17
+        // flutter_local_notifications 需要 core library desugaring
+        isCoreLibraryDesugaringEnabled = true
     }
 
     kotlinOptions {
@@ -42,3 +44,7 @@ android {
 flutter {
     source = "../.."
 }
+
+dependencies {
+    coreLibraryDesugaring("com.android.tools:desugar_jdk_libs:2.1.4")
+}

android/app/src/main/AndroidManifest.xml

@@ -1,6 +1,11 @@
 <manifest xmlns:android="http://schemas.android.com/apk/res/android">
     <!-- 访问局域网后端接口（release 包也需要） -->
     <uses-permission android:name="android.permission.INTERNET"/>
+    <!-- Android 13+ 展示系统通知 -->
+    <uses-permission android:name="android.permission.POST_NOTIFICATIONS"/>
+    <!-- 后台保持进程存活，持续轮询派单消息 -->
+    <uses-permission android:name="android.permission.FOREGROUND_SERVICE"/>
+    <uses-permission android:name="android.permission.FOREGROUND_SERVICE_DATA_SYNC"/>
     <application
         android:label="smart_grid_iot_app_flutter"
         android:name="${applicationName}"
@@ -28,6 +33,11 @@
                 <category android:name="android.intent.category.LAUNCHER"/>
             </intent-filter>
         </activity>
+        <!-- 后台保活：让 App 退到后台后仍能轮询站内消息 -->
+        <service
+            android:name=".KeepAliveService"
+            android:exported="false"
+            android:foregroundServiceType="dataSync"/>
         <!-- Don't delete the meta-data below.
              This is used by the Flutter tool to generate GeneratedPluginRegistrant.java -->
         <meta-data

android/app/src/main/kotlin/com/voltlink/smart_grid_iot_app_flutter/KeepAliveService.kt

@@ -0,0 +1,66 @@
+package com.voltlink.smart_grid_iot_app_flutter
+
+import android.app.Notification
+import android.app.NotificationChannel
+import android.app.NotificationManager
+import android.app.Service
+import android.content.Context
+import android.content.Intent
+import android.os.Build
+import android.os.IBinder
+
+/**
+ * 前台服务：仅用于让进程在退到后台后保持存活，
+ * 从而让 Flutter 侧的 30s 轮询继续运行并弹出系统通知。
+ *
+ * 它不是推送通道：用户手动「强行停止」或清理后台后仍会中断。
+ */
+class KeepAliveService : Service() {
+    companion object {
+        private const val CHANNEL_ID = "voltlink_keepalive"
+        private const val NOTIFICATION_ID = 1001
+    }
+
+    override fun onBind(intent: Intent?): IBinder? = null
+
+    override fun onCreate() {
+        super.onCreate()
+        createChannel()
+    }
+
+    override fun onStartCommand(intent: Intent?, flags: Int, startId: Int): Int {
+        startForeground(NOTIFICATION_ID, buildNotification())
+        return START_STICKY
+    }
+
+    private fun createChannel() {
+        if (Build.VERSION.SDK_INT >= Build.VERSION_CODES.O) {
+            val manager = getSystemService(Context.NOTIFICATION_SERVICE) as NotificationManager
+            if (manager.getNotificationChannel(CHANNEL_ID) == null) {
+                val channel = NotificationChannel(
+                    CHANNEL_ID,
+                    "后台接单提醒",
+                    NotificationManager.IMPORTANCE_MIN
+                )
+                channel.description = "保持 App 运行以接收派单消息"
+                channel.setShowBadge(false)
+                manager.createNotificationChannel(channel)
+            }
+        }
+    }
+
+    private fun buildNotification(): Notification {
+        val builder = if (Build.VERSION.SDK_INT >= Build.VERSION_CODES.O) {
+            Notification.Builder(this, CHANNEL_ID)
+        } else {
+            @Suppress("DEPRECATION")
+            Notification.Builder(this)
+        }
+        return builder
+            .setContentTitle("VoltLink 正在后台运行")
+            .setContentText("用于及时接收派单消息")
+            .setSmallIcon(R.mipmap.ic_launcher)
+            .setOngoing(true)
+            .build()
+    }
+}

android/app/src/main/kotlin/com/voltlink/smart_grid_iot_app_flutter/MainActivity.kt

@@ -1,5 +1,37 @@
 package com.voltlink.smart_grid_iot_app_flutter
 
+import android.content.Intent
 import io.flutter.embedding.android.FlutterActivity
+import io.flutter.embedding.engine.FlutterEngine
+import io.flutter.plugin.common.MethodChannel
 
-class MainActivity : FlutterActivity()
+class MainActivity : FlutterActivity() {
+    private val channelName = "voltlink/keepalive"
+
+    override fun configureFlutterEngine(flutterEngine: FlutterEngine) {
+        super.configureFlutterEngine(flutterEngine)
+        MethodChannel(flutterEngine.dartExecutor.binaryMessenger, channelName)
+            .setMethodCallHandler { call, result ->
+                when (call.method) {
+                    "start" -> {
+                        startKeepAlive()
+                        result.success(null)
+                    }
+                    "stop" -> {
+                        stopService(Intent(this, KeepAliveService::class.java))
+                        result.success(null)
+                    }
+                    else -> result.notImplemented()
+                }
+            }
+    }
+
+    private fun startKeepAlive() {
+        val intent = Intent(this, KeepAliveService::class.java)
+        if (android.os.Build.VERSION.SDK_INT >= android.os.Build.VERSION_CODES.O) {
+            startForegroundService(intent)
+        } else {
+            startService(intent)
+        }
+    }
+}