Gradescope grader page: read rubric state from SubmissionGrader props

On a Gradescope question grade page, the React props in [data-react-class="SubmissionGrader"] (data-react-props JSON) hold the applied rubric items in rubric_item_evaluations (each {rubric_item_id, present}), plus submission.graded and submission.score; rubric_item_applications was empty in this case. For bulk saves from the logged-in page, read this before each save to skip submissions already graded by someone else, then read it again after the save to confirm the items. Fetching the /grade URL with Accept text/html and parsing it with DOMParser works without navigating. Long in-page loops can exceed the browser tool's 45 s script timeout, so start them without await, store progress on window, and poll.