feat: add Fear & Greed filter to entry logic

- core/fng.py: F&G API wrapper with 1h cache (alternative.me)
  - FNG_MIN_ENTRY=41 (env-configurable), blocks entry below threshold
- core/strategy.py: call is_entry_allowed() before volume/regime checks
- daemon/runner.py: log F&G status on every scan cycle
- core/notify.py: include F&G value in buy/signal/status notifications
- core/trader.py: pass current F&G value to notify_buy

Backtest evidence (1y / 18 tickers / 1h candles):
  - No filter:   820 trades, 32.7% WR, avg +0.012%, KRW +95k
  - F&G >= 41:   372 trades, 39.5% WR, avg +0.462%, KRW +1.72M
  - Blocked 452 trades (avg -0.372%, saved ~1.68M KRW loss)

Also add:
- backtest_db.py: Oracle DB storage for backtest runs/results/trades
- fng_1y_backtest.py, fng_adaptive_backtest.py, fng_sim_comparison.py

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

core/fng.py

@@ -0,0 +1,71 @@
+"""공포탐욕지수(F&G) 조회 모듈.
+
+alternative.me API로 일일 F&G 값을 가져와 메모리에 캐시한다.
+캐시 TTL은 1시간 (F&G는 하루 1회 업데이트).
+
+환경변수:
+  FNG_MIN_ENTRY (기본값 41): 이 값 미만이면 진입 차단
+"""
+from __future__ import annotations
+
+import json
+import logging
+import os
+import time
+import urllib.request
+from datetime import datetime
+
+logger = logging.getLogger(__name__)
+
+FNG_MIN_ENTRY = int(os.getenv("FNG_MIN_ENTRY", "41"))  # 진입 허용 최소 F&G 값
+_FNG_API_URL  = "https://api.alternative.me/fng/?limit=1&format=json"
+_CACHE_TTL    = 3600  # 1시간
+
+_fng_value: int | None  = None
+_fng_cached_at: float   = 0.0
+_fng_date_str:  str     = ""
+
+
+def get_fng() -> int:
+    """오늘의 F&G 지수 반환 (0~100). API 실패 시 50(중립) 반환."""
+    global _fng_value, _fng_cached_at, _fng_date_str
+
+    now = time.time()
+    if _fng_value is not None and (now - _fng_cached_at) < _CACHE_TTL:
+        return _fng_value
+
+    try:
+        with urllib.request.urlopen(_FNG_API_URL, timeout=5) as r:
+            data = json.loads(r.read())
+        entry = data["data"][0]
+        _fng_value    = int(entry["value"])
+        _fng_cached_at = now
+        _fng_date_str  = entry.get("timestamp", "")
+        logger.info(
+            f"[F&G] 지수={_fng_value} ({entry.get('value_classification','')}) "
+            f"날짜={datetime.fromtimestamp(int(_fng_date_str)).strftime('%Y-%m-%d') if _fng_date_str else '?'}"
+        )
+    except Exception as e:
+        logger.warning(f"[F&G] API 조회 실패: {e} → 캐시/중립값 사용")
+        if _fng_value is None:
+            _fng_value = 50  # 폴백: 중립
+
+    return _fng_value  # type: ignore[return-value]
+
+
+def is_entry_allowed() -> bool:
+    """현재 F&G 기준으로 진입 허용 여부 반환.
+
+    F&G ≥ FNG_MIN_ENTRY(41) 이면 True.
+    극공포/공포 구간(< 41)이면 False → 진입 차단.
+    """
+    fv = get_fng()
+    allowed = fv >= FNG_MIN_ENTRY
+    if not allowed:
+        label = (
+            "극공포" if fv <= 25 else
+            "공포" if fv <= 40 else
+            "약공포"
+        )
+        logger.info(f"[F&G] 진입 차단 — F&G={fv} ({label}) < {FNG_MIN_ENTRY}")
+    return allowed