fix: silence notification and media opt-in warnings

Suppress the safe notification permission lint after explicit runtime gating.

Opt ChatScreen into Media3 unstable APIs at the file level for the shared media pipeline.

android/app/src/main/java/ru/daemonlord/messenger/core/notifications/NotificationDispatcher.kt

@@ -1,3 +1,5 @@
+@file:Suppress("MissingPermission")
+
 package ru.daemonlord.messenger.core.notifications
 
 import android.Manifest

android/app/src/main/java/ru/daemonlord/messenger/ui/chat/ChatScreen.kt

@@ -1,3 +1,5 @@
+@file:OptIn(UnstableApi::class)
+
 package ru.daemonlord.messenger.ui.chat
 
 import android.Manifest