P2: print→logging 전환, 포트폴리오 중복 제거, Docker healthcheck 추가

- backend/main.py: logging 모듈 도입, print() 제거
- stock-lab/main.py: print() → logger 전환, _calc_portfolio_totals 공용 함수 추출
- stock-lab/scraper.py: logging 모듈 도입, print() 제거
- docker-compose.yml: 전 서비스 healthcheck 블록 추가 (30s 간격, 3회 재시도)

Co-Authored-By: Claude Opus 4.6 <noreply@anthropic.com>

stock-lab/app/scraper.py

@@ -1,8 +1,11 @@
+import logging
 import requests
 from bs4 import BeautifulSoup
 from typing import List, Dict, Any
 import time
 
+logger = logging.getLogger("stock-lab.scraper")
+
 # 네이버 파이낸스 주요 뉴스
 NAVER_FINANCE_NEWS_URL = "https://finance.naver.com/news/mainnews.naver"
 # 해외증시 뉴스 (모바일 API 사용)
@@ -73,7 +76,7 @@ def fetch_market_news() -> List[Dict[str, str]]:
         return articles
 
     except Exception as e:
-        print(f"[StockLab] Scraping failed: {e}")
+        logger.error(f"국내 뉴스 스크래핑 실패: {e}")
         return []
 
 def fetch_overseas_news() -> List[Dict[str, str]]:
@@ -126,7 +129,7 @@ def fetch_overseas_news() -> List[Dict[str, str]]:
         return articles
 
     except Exception as e:
-        print(f"[StockLab] Overseas news failed: {e}")
+        logger.error(f"해외 뉴스 스크래핑 실패: {e}")
         return []
 
 def fetch_major_indices() -> Dict[str, Any]:
@@ -237,7 +240,7 @@ def fetch_major_indices() -> Dict[str, Any]:
                 })
 
         except Exception as e:
-             print(f"[StockLab] World indices failed: {e}")
+             logger.error(f"해외 지수 스크래핑 실패: {e}")
              
         # --- 환율 (USD/KRW) ---
         try:
@@ -269,10 +272,10 @@ def fetch_major_indices() -> Dict[str, Any]:
                     "type": "exchange"
                 })
         except Exception as e:
-            print(f"[StockLab] Exchange rate failed: {e}")
+            logger.error(f"환율 스크래핑 실패: {e}")
         
         return {"indices": indices, "crawled_at": time.strftime("%Y-%m-%d %H:%M:%S")}
         
     except Exception as e:
-        print(f"[StockLab] Indices scraping failed: {e}")
+        logger.error(f"지수 스크래핑 전체 실패: {e}")
         return {"indices": [], "error": str(e)}