Add boilerplate code, Docker environment, Makefile etc.

src/Dependencies.php

@@ -0,0 +1,41 @@
+<?php
+declare(strict_types=1);
+
+namespace MailAccountAdmin;
+
+use DI\Container;
+use MailAccountAdmin\Login\LoginController;
+use Psr\Container\ContainerInterface;
+use Slim\Views\Twig;
+
+class Dependencies
+{
+    private const SETTINGS = 'settings';
+    private const TWIG = 'view';
+    private const TWIG_TEMPLATE_DIR = __DIR__ . '/../templates';
+
+    public static function createContainer(Settings $settings): Container
+    {
+        $container = new Container();
+
+        // App settings
+        $container->set(self::SETTINGS, $settings);
+
+        // Twig template engine
+        $container->set(self::TWIG, function (ContainerInterface $c) {
+            /** @var Settings $settings */
+            $settings = $c->get(self::SETTINGS);
+
+            return Twig::create(self::TWIG_TEMPLATE_DIR, $settings->getTwigSettings());
+        });
+
+        // Login, registration, authentication
+        $container->set(LoginController::class, function (ContainerInterface $c) {
+            return new LoginController(
+                $c->get(self::TWIG)
+            );
+        });
+
+        return $container;
+    }
+}