feat: implement user registration email notification and add email templates

backend/app/Mail/UserRegistrationCompleted.php

@@ -0,0 +1,61 @@
+<?php
+
+namespace App\Mail;
+
+use Illuminate\Bus\Queueable;
+use Illuminate\Mail\Mailables\Address;
+use Illuminate\Mail\Mailable;
+use Illuminate\Mail\Mailables\Content;
+use Illuminate\Mail\Mailables\Envelope;
+use Illuminate\Queue\SerializesModels;
+
+class UserRegistrationCompleted extends Mailable
+{
+    use Queueable, SerializesModels;
+
+    private string $name;
+    private string $password;
+
+    /**
+     * Create a new message instance.
+     */
+    public function __construct(string $name, string $password)
+    {
+        $this->name = $name;
+        $this->password = $password;
+    }
+
+    /**
+     * Get the message envelope.
+     */
+    public function envelope(): Envelope
+    {
+        return new Envelope(
+            subject: '[ISOP] Účet vytvorený',
+        );
+    }
+
+    /**
+     * Get the message content definition.
+     */
+    public function content(): Content
+    {
+        return new Content(
+            view: 'mail.registration.completed',
+            with: [
+                "name" => $this->name,
+                "password" => $this->password
+            ]
+        );
+    }
+
+    /**
+     * Get the attachments for the message.
+     *
+     * @return array<int, \Illuminate\Mail\Mailables\Attachment>
+     */
+    public function attachments(): array
+    {
+        return [];
+    }
+}