CRITICAL FIX: TP/SL orders using wrong size calculation

**ROOT CAUSE:** placeExitOrders() calculated position size using TP/SL prices instead of entry price

**Problem:**
- TP1 order size: 85 / TP1_price (00.746) = 2.914 SOL
- Actual position: 80 / entry_price (99.946) = 3.901 SOL
- TP1 should close: 3.901 * 75% = 2.926 SOL
- But it only closed: 2.914 SOL = 74.7% ❌ WRONG!

**Result:** TP1 closed ~25% instead of 75%, no runner left

**Fix:**
- Changed usdToBase() to use entryPrice for ALL size calculations
- Added entryPrice param to PlaceExitOrdersOptions interface
- Updated all API routes to pass entryPrice

**Testing:** Next trade will have correctly sized TP/SL orders

app/api/trading/reduce-position/route.ts

@@ -201,6 +201,7 @@ export async function POST(request: NextRequest): Promise<NextResponse<ReducePos
       symbol: trade.symbol,
       direction: trade.direction,
       positionSizeUSD: remainingSizeUSD,
+      entryPrice: trade.entryPrice,
       tp1Price: newTP1,
       tp2Price: newTP2,
       stopLossPrice: newSL,