Add new Shopware 6 role with OIDC/LDAP plugin integration and Docker-based deployment configuration.

Includes:
- New role: web-app-shopware (Docker, MariaDB, Redis, OpenSearch)
- Updated networks and ports configuration
- Automated install, migration, and admin creation
- Optional IAM integration via OIDC/LDAP plugins

Reference: https://chatgpt.com/share/6907b0d4-ab14-800f-b576-62c0d26c8ad1

roles/web-app-shopware/schema/main.yml

@@ -0,0 +1,2 @@
+# Minimal schema placeholder (extend with your own config contract if desired)
+credentials: {}