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/main.py

@@ -66,10 +66,22 @@ def is_market_open(d: date_type) -> bool:
     return d.weekday() < 5 and d.strftime("%Y-%m-%d") not in _HOLIDAYS
 
 
+def _calc_portfolio_totals(items, prices):
+    """포트폴리오 총 매입/평가금 계산 (snapshot과 API에서 공용)"""
+    total_buy = 0
+    total_eval = 0
+    for item in items:
+        buy_amount = item["avg_price"] * item["quantity"]
+        current_price = prices.get(item["ticker"], item["avg_price"])
+        total_buy += buy_amount
+        total_eval += current_price * item["quantity"]
+    return total_buy, total_eval
+
+
 def save_daily_snapshot():
     today = date_type.today()
     if not is_market_open(today):
-        print(f"[Snapshot] {today} 휴장일 — 스킵")
+        logger.info(f"Snapshot: {today} 휴장일 — 스킵")
         return
 
     today_str = today.strftime("%Y-%m-%d")
@@ -80,16 +92,13 @@ def save_daily_snapshot():
     if items:
         tickers = list({item["ticker"] for item in items})
         prices = get_current_prices(tickers)
-        total_eval = sum(
-            prices.get(item["ticker"], item["avg_price"]) * item["quantity"]
-            for item in items
-        )
+        _, total_eval = _calc_portfolio_totals(items, prices)
     else:
         total_eval = 0
 
     total_assets = total_eval + total_cash
     upsert_asset_snapshot(today_str, total_eval, total_cash, total_assets)
-    print(f"[Snapshot] {today_str} 저장 완료: eval={total_eval}, cash={total_cash}, total={total_assets}")
+    logger.info(f"Snapshot: {today_str} 저장 — eval={total_eval}, cash={total_cash}, total={total_assets}")
 
 @app.on_event("startup")
 def on_startup():
@@ -108,7 +117,7 @@ def on_startup():
     scheduler.start()
 
 def run_scraping_job():
-    print("[StockLab] Starting news scraping...")
+    logger.info("뉴스 스크래핑 시작")
     
     # 1. 국내
     articles_kr = fetch_market_news()
@@ -119,7 +128,7 @@ def run_scraping_job():
     # count_world = save_articles(articles_world)
     count_world = 0
     
-    print(f"[StockLab] Saved {count_kr} domestic, {count_world} overseas articles.")
+    logger.info(f"스크래핑 완료: 국내 {count_kr}건, 해외 {count_world}건")
 
 @app.get("/health")
 def health():