fix: pass correct parameter for borrow boxes in subtraction

The subtraction template was receiving showBorrowNotation (scratch work boxes)
for the show-borrows parameter instead of showCarryBoxes (borrow box row).
This caused the 'Borrow Boxes' setting to have no effect, and borrow boxes
were incorrectly controlled by the 'Borrowed 10s Box' setting instead.

Changes:
- Line 221: Change problem.showBorrowNotation to problem.showCarryBoxes
- First parameter is show-borrows (borrow box row visibility)
- Sixth parameter is show-borrow-notation (scratch work boxes)

Now the 'Borrow Boxes' scaffolding setting correctly controls the borrow
boxes row in subtraction problems.

🤖 Generated with [Claude Code](https://claude.com/claude-code)

Co-Authored-By: Claude <noreply@anthropic.com>

apps/web/src/app/create/worksheets/typstGenerator.ts

@@ -218,7 +218,7 @@ ${generateSubtractionProblemStackFunction(cellSize, maxDigits)}
       } else {
         subtraction-problem-stack(
           problem.minuend, problem.subtrahend, index,
-          problem.showBorrowNotation,  // show-borrows (whether to show borrow boxes)
+          problem.showCarryBoxes,      // show-borrows (whether to show borrow boxes)
           problem.showAnswerBoxes,
           problem.showPlaceValueColors,
           problem.showTenFrames,