feat(local-secrets): introduce unified local secrets management and documentation

- Add example secret files for `app_key`, `db_user_password`, and `redis_password`.
- Introduce `local.vault.yml.example` for Ansible Vault encryption of local secrets.
- Create migration and setup scripts for transitioning from `.env.local` to secrets files.
- Update `docker-compose.local.yml` to adopt Docker Secrets and `_FILE` pattern for local configurations.
- Add deployment playbooks and enhanced logging configurations for local development.

docker/php/zz-docker.conf

@@ -8,7 +8,8 @@ user = appuser
 group = appuser
 
 ; The address on which to accept FastCGI requests.
-listen = 9000
+; Use 0.0.0.0:9000 to listen on all interfaces (required for Docker networking)
+listen = 0.0.0.0:9000
 
 ; Clear environment in FPM workers
 clear_env = no