feat(story-1.1): scaffold Symfony 7.4 LTS app with DDEV, Messenger, Scheduler

- DDEV config: PHP 8.4, PostgreSQL 16, nginx-fpm, Imagick via webimage_extra_packages
- Symfony 7.4 LTS skeleton + webapp pack scaffolded via Composer
- Removed AssetMapper, Stimulus, UX-Turbo (replaced by Vue 3 SPA per architecture)
- Added symfony/messenger + symfony/scheduler (Doctrine transport)
- Gitea CI workflow: PHP 8.4 container + PostgreSQL 16 service, runs phpunit

Co-Authored-By: Claude Sonnet 4.6 <noreply@anthropic.com>

public/index.php

@@ -0,0 +1,9 @@
+<?php
+
+use App\Kernel;
+
+require_once dirname(__DIR__).'/vendor/autoload_runtime.php';
+
+return static function (array $context) {
+    return new Kernel($context['APP_ENV'], (bool) $context['APP_DEBUG']);
+};