feat: implement NotFoundResponse and ServerErrorResponse classes with corresponding tests

tests/Http/Responses/NotFoundResponseTest.php

@@ -0,0 +1,22 @@
+<?php
+
+namespace Siteworxpro\Tests\Http\Responses;
+
+use Siteworxpro\App\Http\Responses\NotFoundResponse;
+use Siteworxpro\Tests\Unit;
+
+class NotFoundResponseTest extends Unit
+{
+    public function testToArray(): void
+    {
+        $response = new NotFoundResponse('/api/resource', ['key' => 'value']);
+
+        $expected = [
+            'status_code' => 404,
+            'message' => 'The requested resource /api/resource was not found.',
+            'context' => ['key' => 'value'],
+        ];
+
+        $this->assertEquals($expected, $response->toArray());
+    }
+}