Scaffold Symfony 8 app with Bootstrap/DataTables and Docker stack

- Symfony 8.1 webapp skeleton on PHP 8.5 (AssetMapper/importmap, no Node)
- Form-login gate: User entity, security.yaml, SecurityController,
  app:user:create command, initial migration (user + messenger_messages)
- Bootstrap 5 + DataTables layout (base/login/home templates); any
  table.datatable is auto-initialised
- trusted_proxies/headers wired for the shared Nginx Proxy Manager
- Docker (servers only): docker-compose.yml (php:8.5-fpm-alpine,
  nginx:1.30-alpine, mariadb:12.3; host ports 8085/3310; external
  docker_default network) + docker/{Dockerfile,php.ini,nginx,setup.sh,restart.sh}
- .env with CHANGEME placeholders (no secrets), .gitattributes enforces
  LF so the deploy scripts stay runnable on Linux

Co-Authored-By: Claude Sonnet 5 <noreply@anthropic.com>

.gitignore

@@ -0,0 +1,23 @@
+
+###> symfony/framework-bundle ###
+/.env.local
+/.env.local.php
+/.env.*.local
+/config/secrets/prod/prod.decrypt.private.php
+/public/bundles/
+/var/
+/vendor/
+###< symfony/framework-bundle ###
+
+###> phpunit/phpunit ###
+/phpunit.xml
+/.phpunit.cache/
+###< phpunit/phpunit ###
+
+###> symfony/asset-mapper ###
+/public/assets/
+/assets/vendor/
+###< symfony/asset-mapper ###
+
+# JetBrains IDE metadata (local, machine-specific)
+/.idea/