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/packages/cache.yaml

@@ -0,0 +1,19 @@
+framework:
+    cache:
+        # Unique name of your app: used to compute stable namespaces for cache keys.
+        #prefix_seed: your_vendor_name/app_name
+
+        # The "app" cache stores to the filesystem by default.
+        # The data in this cache should persist between deploys.
+        # Other options include:
+
+        # Redis
+        #app: cache.adapter.redis
+        #default_redis_provider: redis://localhost
+
+        # APCu (not recommended with heavy random-write workloads as memory fragmentation can cause perf issues)
+        #app: cache.adapter.apcu
+
+        # Namespaced pools use the above "app" backend by default
+        #pools:
+            #my.dedicated.cache: null