feat: Implement ATR-based dynamic TP2 system and fix P&L calculation

- Add ATR-based dynamic TP2 scaling from 0.7% to 3.0% based on volatility
- New config options: useAtrBasedTargets, atrMultiplierForTp2, minTp2Percent, maxTp2Percent
- Enhanced settings UI with ATR controls and updated risk calculator
- Fix external closure P&L calculation using unrealized P&L instead of volatile current price
- Update execute and test endpoints to use calculateDynamicTp2() function
- Maintain 25% runner system for capturing extended moves (4-5% targets)
- Add environment variables for ATR-based configuration
- Better P&L accuracy for manual position closures

.env

@@ -105,7 +105,22 @@ TAKE_PROFIT_2_PERCENT=0.7
 
 # Take Profit 2 Size: What % of remaining position to close at TP2
 # Example: 100 = close all remaining position
-TAKE_PROFIT_2_SIZE_PERCENT=75
+TAKE_PROFIT_2_SIZE_PERCENT=0
+
+# ATR-based dynamic targets (capture big moves like 4-5% drops)
+# Enable dynamic TP2 based on market volatility
+USE_ATR_BASED_TARGETS=true
+
+# ATR multiplier for TP2 calculation (TP2 = ATR × this value)
+# Example: ATR=0.8% × 2.0 = 1.6% TP2 target
+ATR_MULTIPLIER_FOR_TP2=2.0
+
+# Minimum TP2 level regardless of ATR (safety floor)
+MIN_TP2_PERCENT=0.7
+
+# Maximum TP2 level cap (prevents excessive targets)
+# Example: 3.0% = 30% account gain at 10x leverage
+MAX_TP2_PERCENT=3.0
 
 # Emergency Stop: Hard stop if this level is breached
 # Example: -2.0% on 10x = -20% account loss (rare but protects from flash crashes)