fix: post placeholder foreground notification immediately on play

startForegroundService() requires startForeground() within ~5 seconds.
The async coroutine (DB queries, old job join) delayed the Media3
notification pipeline past this deadline. Now we:
- Create the media session in onCreate() instead of lazily
- Post a minimal "Connecting…" notification synchronously in
  onStartCommand before launching the async play coroutine
- Media3 replaces it with the proper media notification once the
  adapter state updates to Playing

Made-with: Cursor

app/src/main/java/xyz/cottongin/radio247/service/RadioPlaybackService.kt

@@ -1,5 +1,7 @@
 package xyz.cottongin.radio247.service
 
+import android.app.NotificationChannel
+import android.app.NotificationManager
 import android.app.PendingIntent
 import android.content.Context
 import android.content.Intent
@@ -10,6 +12,8 @@ import android.net.NetworkRequest
 import android.os.Bundle
 import android.os.PowerManager
 import android.util.Log
+import androidx.core.app.NotificationCompat
+import xyz.cottongin.radio247.R
 import com.google.common.util.concurrent.SettableFuture
 import androidx.media3.common.MediaItem
 import androidx.media3.common.MediaMetadata
@@ -55,6 +59,8 @@ class ConnectionFailedException(cause: Throwable) : Exception("Connection failed
 class RadioPlaybackService : MediaLibraryService() {
     companion object {
         private const val TAG = "RadioPlayback"
+        private const val FOREGROUND_CHANNEL_ID = "radio_playback"
+        private const val FOREGROUND_NOTIFICATION_ID = 1
         const val ACTION_PLAY = "xyz.cottongin.radio247.PLAY"
         const val ACTION_STOP = "xyz.cottongin.radio247.STOP"
         const val ACTION_PAUSE = "xyz.cottongin.radio247.PAUSE"
@@ -118,6 +124,24 @@ class RadioPlaybackService : MediaLibraryService() {
 
     override fun onCreate() {
         super.onCreate()
+        ensureForegroundChannel()
+        ensureMediaSession()
+    }
+
+    private fun ensureForegroundChannel() {
+        val channel = NotificationChannel(
+            FOREGROUND_CHANNEL_ID, "Radio Playback", NotificationManager.IMPORTANCE_LOW
+        )
+        getSystemService(NotificationManager::class.java).createNotificationChannel(channel)
+    }
+
+    private fun postPlaceholderForeground() {
+        val notification = NotificationCompat.Builder(this, FOREGROUND_CHANNEL_ID)
+            .setSmallIcon(R.drawable.ic_notification)
+            .setContentTitle("Connecting…")
+            .setSilent(true)
+            .build()
+        startForeground(FOREGROUND_NOTIFICATION_ID, notification)
     }
 
     override fun onStartCommand(intent: Intent?, flags: Int, startId: Int): Int {
@@ -126,6 +150,7 @@ class RadioPlaybackService : MediaLibraryService() {
             ACTION_PLAY -> {
                 val stationId = intent.getLongExtra(EXTRA_STATION_ID, -1L)
                 if (stationId >= 0) {
+                    postPlaceholderForeground()
                     launchPlay(stationId)
                 } else {
                     stopSelf()
@@ -194,7 +219,6 @@ class RadioPlaybackService : MediaLibraryService() {
         }
 
         acquireLocks()
-        ensureMediaSession()
         playerAdapter?.updateStation(station)
         playerAdapter?.updatePlaybackState(PlaybackState.Connecting(station))