feat: add pre-market planner config and remove static watchlists (issue #78)

- Add pre-market planner settings: PRE_MARKET_MINUTES, MAX_SCENARIOS_PER_STOCK,
  PLANNER_TIMEOUT_SECONDS, DEFENSIVE_PLAYBOOK_ON_FAILURE, RESCAN_INTERVAL_SECONDS
- Change ENABLED_MARKETS default from KR to KR,US
- Remove static WATCHLISTS and STOCK_UNIVERSE dictionaries from main.py
- Replace watchlist-based trading with dynamic scanner-only stock discovery
- SmartVolatilityScanner is now the sole source of trading candidates
- Add active_stocks dict for scanner-discovered stocks per market
- Add smart_scanner parameter to run_daily_session()

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

src/config.py

@@ -55,8 +55,15 @@ class Settings(BaseSettings):
     DAILY_SESSIONS: int = Field(default=4, ge=1, le=10)
     SESSION_INTERVAL_HOURS: int = Field(default=6, ge=1, le=24)
 
+    # Pre-Market Planner
+    PRE_MARKET_MINUTES: int = Field(default=30, ge=10, le=120)
+    MAX_SCENARIOS_PER_STOCK: int = Field(default=5, ge=1, le=10)
+    PLANNER_TIMEOUT_SECONDS: int = Field(default=60, ge=10, le=300)
+    DEFENSIVE_PLAYBOOK_ON_FAILURE: bool = True
+    RESCAN_INTERVAL_SECONDS: int = Field(default=300, ge=60, le=900)
+
     # Market selection (comma-separated market codes)
-    ENABLED_MARKETS: str = "KR"
+    ENABLED_MARKETS: str = "KR,US"
 
     # Backup and Disaster Recovery (optional)
     BACKUP_ENABLED: bool = True