feat(email): add a separate notification sender to the instance email settings

Team notifications sent through the instance email settings, the S3
connection error alert, and the channel disabled alert now use the
optional notification from address and name. Account mails keep the
default sender. Remove the unused emails command and its views.

database/migrations/2026_11_03_194650_add_notification_sender_to_instance_settings_table.php

@@ -0,0 +1,23 @@
+<?php
+
+use Illuminate\Database\Migrations\Migration;
+use Illuminate\Database\Schema\Blueprint;
+use Illuminate\Support\Facades\Schema;
+
+return new class extends Migration
+{
+    public function up(): void
+    {
+        Schema::table('instance_settings', function (Blueprint $table) {
+            $table->text('notification_from_address')->nullable();
+            $table->text('notification_from_name')->nullable();
+        });
+    }
+
+    public function down(): void
+    {
+        Schema::table('instance_settings', function (Blueprint $table) {
+            $table->dropColumn(['notification_from_address', 'notification_from_name']);
+        });
+    }
+};