Refactor notifications (#4883)

Also fixes https://github.com/tuskyapp/Tusky/issues/4858.
But apart from that there should be no functional change.

app/src/main/java/com/keylesspalace/tusky/di/NotificationManagerModule.kt

@@ -0,0 +1,33 @@
+/* Copyright 2025 Tusky contributors
+ *
+ * This file is a part of Tusky.
+ *
+ * This program is free software; you can redistribute it and/or modify it under the terms of the
+ * GNU General Public License as published by the Free Software Foundation; either version 3 of the
+ * License, or (at your option) any later version.
+ *
+ * Tusky is distributed in the hope that it will be useful, but WITHOUT ANY WARRANTY; without even
+ * the implied warranty of MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU General
+ * Public License for more details.
+ *
+ * You should have received a copy of the GNU General Public License along with Tusky; if not,
+ * see <http://www.gnu.org/licenses>. */
+
+package com.keylesspalace.tusky.di
+
+import android.app.NotificationManager
+import android.content.Context
+import dagger.Module
+import dagger.Provides
+import dagger.hilt.InstallIn
+import dagger.hilt.android.qualifiers.ApplicationContext
+import dagger.hilt.components.SingletonComponent
+
+@Module
+@InstallIn(SingletonComponent::class)
+object NotificationManagerModule {
+    @Provides
+    fun providesNotificationManager(@ApplicationContext appContext: Context): NotificationManager {
+        return appContext.getSystemService(Context.NOTIFICATION_SERVICE) as NotificationManager
+    }
+}