add android MessagingStyle for chat notifications

Patches expo-notifications to use NotificationCompat.MessagingStyle
for chat-message and chat-reaction notifications. Downloads the sender
avatar thumbnail and creates a Person with the icon for the
conversation-style notification layout.

Co-Authored-By: Claude Opus 4.6 (1M context) <noreply@anthropic.com>

modules/expo-background-notification-handler/android/src/main/java/expo/modules/backgroundnotificationhandler/BackgroundNotificationHandler.kt

@@ -1,7 +1,9 @@
 package expo.modules.backgroundnotificationhandler
 
 import android.content.Context
+import android.util.Log
 import com.google.firebase.messaging.RemoteMessage
+import org.json.JSONObject
 
 class BackgroundNotificationHandler(
   private val context: Context,
@@ -13,8 +15,12 @@ class BackgroundNotificationHandler(
       return
     }
 
-    if (remoteMessage.data["reason"] == "chat-message" || remoteMessage.data["reason"] == "chat-reaction") {
+    val reason = remoteMessage.data["reason"]
+    Log.d(TAG, "handleMessage: reason=$reason")
+
+    if (reason == "chat-message" || reason == "chat-reaction") {
       mutateWithChatMessage(remoteMessage)
+      packBodyForPresentation(remoteMessage)
     } else {
       mutateWithOtherReason(remoteMessage)
     }
@@ -22,6 +28,18 @@ class BackgroundNotificationHandler(
     notifInterface.showMessage(remoteMessage)
   }
 
+  private fun packBodyForPresentation(remoteMessage: RemoteMessage) {
+    val body = JSONObject().apply {
+      put("reason", remoteMessage.data["reason"])
+      put("senderDisplayName", remoteMessage.data["senderDisplayName"])
+      put("senderAvatarUrl", remoteMessage.data["senderAvatarUrl"])
+      put("senderHandle", remoteMessage.data["senderHandle"])
+      put("convoId", remoteMessage.data["convoId"])
+    }
+    remoteMessage.data["body"] = body.toString()
+    Log.d(TAG, "packBodyForPresentation: $body")
+  }
+
   private fun mutateWithChatMessage(remoteMessage: RemoteMessage) {
     if (NotificationPrefs(context).getBoolean("playSoundChat")) {
       // If oreo or higher
@@ -42,6 +60,10 @@ class BackgroundNotificationHandler(
     remoteMessage.data["badge"] = null
   }
 
+  companion object {
+    private const val TAG = "BGNotifHandler"
+  }
+
   private fun mutateWithOtherReason(remoteMessage: RemoteMessage) {
     // If oreo or higher
     if (android.os.Build.VERSION.SDK_INT >= android.os.Build.VERSION_CODES.O) {