Add captcha image generation functionality.

app/Captcha/Dto/Image.php

@@ -0,0 +1,36 @@
+<?php declare(strict_types=1);
+
+namespace App\Captcha\Dto;
+
+final readonly class Image
+{
+    public function __construct(
+        private string $imageBase64,
+        private int $width,
+        private int $height
+    ) { }
+
+    /**
+     * @return string
+     */
+    public function getImageBase64(): string
+    {
+        return $this->imageBase64;
+    }
+
+    /**
+     * @return int
+     */
+    public function getWidth(): int
+    {
+        return $this->width;
+    }
+
+    /**
+     * @return int
+     */
+    public function getHeight(): int
+    {
+        return $this->height;
+    }
+}