refactor: rename stock-lab → stock (graduation)

- git mv stock-lab/ → stock/
- docker-compose.yml: 서비스 키 + container_name + build.context +
  frontend.depends_on + agent-office STOCK_LAB_URL → STOCK_URL
- agent-office/app: config.py, service_proxy.py, agents/stock.py, tests/
  STOCK_LAB_URL → STOCK_URL
- nginx/default.conf: proxy_pass http://stock-lab → http://stock (3 lines)
- CLAUDE.md / README.md / STATUS.md / scripts/ 문구 갱신
- stock/ 내부 자기 참조 갱신

lab 네이밍 정책 (feedback_lab_naming.md) graduation.
API URL / Python import / DB 파일명 변경 없음.

stock/requirements.txt

@@ -0,0 +1,14 @@
+# 주식 서비스용 라이브러리
+anthropic==0.39.0
+requests==2.32.3
+httpx==0.27.2
+beautifulsoup4==4.12.3
+fastapi==0.115.6
+uvicorn[standard]==0.30.6
+apscheduler==3.10.4
+python-dotenv==1.0.1
+finance-datareader==0.9.110
+lxml==6.1.0
+pytest==8.3.2
+pytest-asyncio==0.24.0
+