fix: Prevent runner positions from being below minimum order size

**Problem:**
When closing small runner positions (5% after TP1+TP2), the calculated size could be below Drift's minimum order size:
- ETH minimum: 0.01 ETH
- After TP1 (75%): 0.0025 ETH left
- After TP2 (80%): 0.0005 ETH runner
- Trailing stop tries to close 0.0005 ETH → ERROR: Below minimum 0.01

n8n showed: "Order size 0.0011 is below minimum 0.01"

**Root Cause:**
closePosition() calculated: sizeToClose = position.size * (percentToClose / 100)
No validation against marketConfig.minOrderSize before submitting to Drift.

**Solution:**
Added minimum size check in closePosition() (lib/drift/orders.ts):
1. Calculate intended close size
2. If below minOrderSize → force 100% close instead
3. Log warning when this happens
4. Prevents Drift API rejection

**Code Change:**
```typescript
let sizeToClose = position.size * (params.percentToClose / 100)

// If calculated size is below minimum, close 100%
if (sizeToClose < marketConfig.minOrderSize) {
  console.log('⚠️ Calculated size below minimum - forcing 100% close')
  sizeToClose = position.size
}
```

**Impact:**
- ✅ Small runner positions close successfully
- ✅ No more "below minimum" errors from Drift
-  Trades complete cleanly
- ⚠️ Runner may close slightly earlier than intended (but better than error)

**Example:**
ETH runner at 0.0005 ETH → tries to close → detects <0.01 → closes entire 0.0005 ETH position at once instead of rejecting.

This is the correct behavior - if the position is already too small, we should close it entirely.

lib/drift/orders.ts

@@ -468,7 +468,15 @@ export async function closePosition(
     }
     
     // Calculate size to close
-    const sizeToClose = position.size * (params.percentToClose / 100)
+    let sizeToClose = position.size * (params.percentToClose / 100)
+    
+    // CRITICAL FIX: If calculated size is below minimum, close 100% instead
+    // This prevents "runner" positions from being too small to close
+    if (sizeToClose < marketConfig.minOrderSize) {
+      console.log(`⚠️ Calculated close size ${sizeToClose.toFixed(4)} is below minimum ${marketConfig.minOrderSize}`)
+      console.log(`   Forcing 100% close to avoid Drift rejection`)
+      sizeToClose = position.size // Close entire position
+    }
     
     console.log(`📝 Close order details:`)
     console.log(`   Current position: ${position.size.toFixed(4)} ${position.side}`)