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>

config/routes.yaml

@@ -0,0 +1,21 @@
+# yaml-language-server: $schema=https://symfony.com/schema/config/routing/routing.yaml
+
+home:
+    path: /
+    controller: App\UI\Http\HomeController::index
+    methods: [GET]
+
+login:
+    path: /login
+    controller: App\UI\Http\Auth\OidcAuthController::login
+    methods: [GET]
+
+auth_callback:
+    path: /auth/callback
+    controller: App\UI\Http\Auth\OidcAuthController::callback
+    methods: [GET]
+
+logout:
+    path: /logout
+    controller: App\UI\Http\Auth\OidcAuthController::logout
+    methods: [GET, POST]