Fix handwriting disappearing when submitting an answer.
The submission renderer now applies the same canvas transform as the on-screen pen canvas, including scaling and vertical cropping. Previously, some captures were blank or misplaced, causing grading to return not graded.
Original strokes in affected attempts are preserved. After updating, use Try again and Submit to recapture the saved handwriting; no rewriting is needed. Request recheck would reuse the old blank image.
A native rendering regression test verifies visible ink across cropped, multi-page submissions.