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/secrets/local.vault.yml.example

@@ -0,0 +1,24 @@
+---
+# Local Development Vault Example
+# Copy this file to local.vault.yml and encrypt with:
+# ansible-vault encrypt local.vault.yml
+#
+# Or use plain text for local development (not recommended for shared machines):
+# ansible-vault encrypt local.vault.yml --vault-password-file ~/.ansible/vault_pass_local.txt
+#
+# For local development, you can also keep it unencrypted if you prefer:
+# cp local.vault.yml.example local.vault.yml
+# # Edit local.vault.yml with your local development secrets
+
+# Database Credentials (Local Development)
+vault_db_password: "local-dev-db-password-change-me"
+
+# Redis Password (Local Development)
+vault_redis_password: "local-dev-redis-password-change-me"
+
+# Application Secrets (Local Development)
+# Generate with: php -r "echo 'base64:' . base64_encode(random_bytes(32));"
+vault_app_key: "base64:local-dev-app-key-change-me-base64-encoded-32-byte-key"
+
+# Optional: Encryption Key (defaults to app_key if not set)
+vault_encryption_key: "base64:local-dev-encryption-key-change-me"