Add environment variable example and update .gitignore

- Created a new .env.example file to provide a template for environment variables, including database connection details, JWT settings, encryption keys, and external API keys.
- Updated .gitignore to include additional test output directories and archive files, ensuring that unnecessary files are not tracked by Git.
- Removed outdated approval test reports and scripts that are no longer needed, streamlining the project structure.

These changes improve the clarity of environment configuration and maintain a cleaner repository.

.gitignore

@@ -218,6 +218,11 @@ docs/mes-reference/
 
 # 테스트 결과물
 frontend/test-results/
+test-output/
+test-results/
+
+# 아카이브/백업 파일
+*.tar.gz
 
 # Cursor 설정
 .cursor/