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- Removed outdated approval test reports and scripts that are no longer needed, streamlining the project structure.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.

backend-node/README_API_SETUP.md

@@ -19,19 +19,19 @@ cp .env.shared .env
 
 ### ✅ 한국은행 환율 API
 - 용도: 환율 정보 조회
-- 키: `OXIGPQXH68NUKVKL5KT9`
+- 키: `${BOK_API_KEY}`
 
 ### ✅ 기상청 API Hub
 - 용도: 날씨특보, 기상정보
-- 키: `ogdXr2e9T4iHV69nvV-IwA`
+- 키: `${KMA_API_KEY}`
 
 ### ✅ ITS 국가교통정보센터
 - 용도: 교통사고, 도로공사 정보
-- 키: `d6b9befec3114d648284674b8fddcc32`
+- 키: `${ITS_API_KEY}`
 
 ### ✅ 한국도로공사 OpenOASIS
 - 용도: 고속도로 교통정보
-- 키: `7820214492`
+- 키: `${EXWAY_API_KEY}`
 
 ---