Add to winning Position Feature
Enable the bot to add to an existing winning position when new valid signals arrive from TradingView.
Risk controls: Do not add if SL would exceed risk cap, if signal contradicts trend, or if total size hits max position size.
Example:
Entry long $100 → price $120 with new buy signal → add 25% of current size; trail stop to breakeven+ after each add; keep partial-TP logic unchanged.