critical: Fix P&L calculation and TP1 false detection bugs

- Add originalPositionSize tracking to prevent stale size usage
- Add price validation to TP1 detection (prevents manual closes misidentified as TP1)
- Fix external closure P&L to use originalPositionSize not currentSize
- Add handleManualClosure method for proper exit reason detection
- Add isPriceAtTarget helper for TP/SL price validation (0.2% tolerance)
- Update all ActiveTrade creation points (execute, test, sync-positions, test-db)

Bug fixes:
- Manual close at 42.34 was detected as TP1 (target 40.71) - FIXED
- P&L showed -$1.71 instead of actual -$2.92 - FIXED
- Exit reason showed SL instead of manual - FIXED

Root cause: Position Manager detected size reduction without validating
price was actually at TP1 level. Used stale currentSize for P&L calculation.

Files modified:
- lib/trading/position-manager.ts (core fixes)
- app/api/trading/execute/route.ts
- app/api/trading/test/route.ts
- app/api/trading/sync-positions/route.ts
- app/api/trading/test-db/route.ts

app/api/trading/test-db/route.ts

@@ -170,6 +170,9 @@ export async function POST(request: NextRequest): Promise<NextResponse<TestTrade
       tp2Price,
       emergencyStopPrice,
       currentSize: positionSizeUSD,
+      originalPositionSize: positionSizeUSD, // Store original size for P&L
+      takeProfitPrice1: tp1Price,
+      takeProfitPrice2: tp2Price,
       tp1Hit: false,
       tp2Hit: false,
       slMovedToBreakeven: false,