CRITICAL FIX: Add transaction confirmation to detect failed orders

- Added getConnection() method to DriftService
- Added proper transaction confirmation in openPosition()
- Check confirmation.value.err to detect on-chain failures
- Return error if transaction fails instead of assuming success
- Prevents phantom trades that never actually execute

This fixes the issue where bot was recording trades with transaction
signatures that don't exist on-chain (like 2gqrPxnvGzdRp56...).

lib/drift/client.ts

@@ -299,6 +299,13 @@ export class DriftService {
     return this.driftClient!
   }
 
+  /**
+   * Get Solana connection instance
+   */
+  getConnection(): Connection {
+    return this.connection
+  }
+
   /**
    * Get user instance
    */