feat : init Central project — Symfony 8 + Nuxt 4 + Docker starter

Same architecture as Lesstime: API Platform 4, JWT auth, @malio/layer-ui,
PostgreSQL 16, Docker Compose (ports 8083/3003/5436), dark mode theme.

Co-Authored-By: Claude Opus 4.6 (1M context) <noreply@anthropic.com>

frontend/layouts/auth.vue

@@ -0,0 +1,7 @@
+<template>
+  <div class="min-h-screen bg-tertiary-500 from-tertiary-500 via-white to-neutral-100 text-neutral-900">
+    <main class="mx-auto flex min-h-screen w-full max-w-[720px] items-center px-6 py-12">
+      <slot />
+    </main>
+  </div>
+</template>