feat: Started demo of backend app

composer.json

@@ -140,7 +140,10 @@
                 "$providers",
                 "providers-console.php"
             ],
-            "routes": "routes.php",
+            "routes": [
+                "routes-backend.php",
+                "routes.php"
+            ],
             "bootstrap": "bootstrap.php",
             "bootstrap-web": [
                 "$bootstrap",

config/routes-backend.php

@@ -0,0 +1,12 @@
+<?php
+
+declare(strict_types=1);
+
+use Yiisoft\Router\Route;
+
+return [
+    Route::get('/app')
+        ->action([\App\Backend\Controllers\SiteController::class, 'index'])
+        ->name('backend/index')
+        ->host('backend.{_host}'),
+];

src/Backend/Controllers/SiteController.php

@@ -0,0 +1,25 @@
+<?php
+
+declare(strict_types=1);
+
+namespace App\Backend\Controllers;
+
+use Psr\Http\Message\ResponseInterface;
+use Yiisoft\Yii\View\ViewRenderer;
+
+class SiteController
+{
+    private ViewRenderer $viewRenderer;
+
+    public function __construct(ViewRenderer $viewRenderer)
+    {
+        $this->viewRenderer = $viewRenderer
+            ->withController($this)
+            ->withViewPath(__DIR__ . '/../views');
+    }
+
+    public function index(): ResponseInterface
+    {
+        return $this->viewRenderer->render('index');
+    }
+}

src/Backend/views/site/index.php

@@ -0,0 +1,51 @@
+<?php
+
+declare(strict_types=1);
+
+use Yiisoft\View\WebView;
+
+/** @var WebView $this */
+$this->setTitle('Backend');
+?>
+
+
+<div class="card mt-3 col-md-8">
+    <div class="card-body">
+        <h2 class="card-title">Welcome to backend</h2>
+    </div>
+</div>
+
+<div class="card mt-3 col-md-8">
+    <div class="card-body">
+        Just example table
+        <table class="table">
+            <thead>
+            <tr>
+                <th scope="col">#</th>
+                <th scope="col">First</th>
+                <th scope="col">Last</th>
+                <th scope="col">Handle</th>
+            </tr>
+            </thead>
+            <tbody>
+            <tr>
+                <th scope="row">1</th>
+                <td>Mark</td>
+                <td>Otto</td>
+                <td>@mdo</td>
+            </tr>
+            <tr>
+                <th scope="row">2</th>
+                <td>Jacob</td>
+                <td>Thornton</td>
+                <td>@fat</td>
+            </tr>
+            <tr>
+                <th scope="row">3</th>
+                <td colspan="2">Larry the Bird</td>
+                <td>@twitter</td>
+            </tr>
+            </tbody>
+        </table>
+    </div>
+</div>