fix: BULLISH confidence 임계값 75로 복원 (#205)

CLAUDE.md 규칙 개정에 따라 BULLISH 시장은 75로 유지.
시장 전망별 임계값: BEARISH=90, NEUTRAL=80, BULLISH=75.

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

src/main.py

@@ -505,8 +505,9 @@ async def trading_cycle(
         outlook = playbook.market_outlook
         if outlook == MarketOutlook.BEARISH:
             min_confidence = 90
+        elif outlook == MarketOutlook.BULLISH:
+            min_confidence = 75
         else:
-            # BULLISH/NEUTRAL: use base threshold (min 80 per CLAUDE.md non-negotiable rule)
             min_confidence = base_threshold
         if match.confidence < min_confidence:
             logger.info(