M0: Skelett + Auth-Grundgerüst (Keycloak-OIDC + API-Token)

- Symfony 7.4 LTS, PHP 8.4, FrankenPHP, SQLite (3-Layer src/UI|Logic|Data)
- Auth: manueller OidcClient (Authorization-Code) im UI-Layer, kein
  Security-Bundle/league; Session-Gate via SessionAuthSubscriber
- API-Guard via statischem X-Api-Token (ApiTokenSubscriber); ExceptionSubscriber
- UserEntity (Auto-Provision) + Init-Migration
- Docker (php:8.4-frankenphp) + compose (essen.ljh31.de, traefik-net external)
- SmokeTests (7) grün: Redirect-Fälle, API-Token, Auth-Render, Logout

Co-Authored-By: Claude Opus 4.8 <noreply@anthropic.com>

src/Kernel.php

@@ -0,0 +1,11 @@
+<?php
+
+namespace App;
+
+use Symfony\Bundle\FrameworkBundle\Kernel\MicroKernelTrait;
+use Symfony\Component\HttpKernel\Kernel as BaseKernel;
+
+class Kernel extends BaseKernel
+{
+    use MicroKernelTrait;
+}