feat: implement admin SMTP settings management and automated order notification system

app/Mail/Admin/AdminOrderNotification.php

@@ -0,0 +1,39 @@
+<?php
+
+declare(strict_types=1);
+
+namespace App\Mail\Admin;
+
+use Illuminate\Bus\Queueable;
+use Illuminate\Mail\Mailable;
+use Illuminate\Mail\Mailables\Content;
+use Illuminate\Mail\Mailables\Envelope;
+use Illuminate\Queue\SerializesModels;
+
+class AdminOrderNotification extends Mailable
+{
+    use Queueable, SerializesModels;
+
+    public function __construct(public readonly array $data) {}
+
+    public function envelope(): Envelope
+    {
+        return new Envelope(
+            subject: '[ADMIN] Đơn hàng mới #' . ($this->data['order_num'] ?? 'N/A')
+                . ' — ' . ($this->data['customer_email'] ?? ''),
+        );
+    }
+
+    public function content(): Content
+    {
+        return new Content(
+            view: 'emails.admin.order-notification',
+            with: $this->data,
+        );
+    }
+
+    public function attachments(): array
+    {
+        return [];
+    }
+}