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.

deployment/ansible/inventory/local.yml

@@ -5,3 +5,7 @@ all:
     localhost:
       ansible_connection: local
       ansible_python_interpreter: "{{ ansible_playbook_python }}"
+  children:
+    local:
+      hosts:
+        localhost: