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/trader.py

@@ -480,8 +480,10 @@ def buy(ticker: str) -> bool:
                 f"{prefix}[매수] {ticker} @ {actual_price:,.0f}원 (실체결가) | "
                 f"수량={amount} | 투자금={order_krw:,}원 | trade_id={trade_id[:8]}"
             )
+            from .fng import get_fng
             notify_buy(ticker, actual_price, amount, order_krw,
-                       max_budget=MAX_BUDGET, per_position=PER_POSITION)
+                       max_budget=MAX_BUDGET, per_position=PER_POSITION,
+                       fng=get_fng())
             return True
         except Exception as e:
             logger.error(f"매수 예외 {ticker}: {e}")