Convert the progress-tab exam attempts fetch (`courseHome.examsData`) to a React Query hook

How it works today

1. course-home/progress-tab/ProgressTab.jsx — ProgressTabContent takes sectionScores from the progress query, flattens every subsection's blockKey into sequenceIds, and calls useGetExamsData(courseId, sequenceIds).
2. course-home/progress-tab/hooks.jsx — useGetExamsData is a useEffect that dispatches fetchExamAttemptsData(courseId, sequenceIds).
3. course-home/data/thunks.js — fetchExamAttemptsData runs Promise.all over the ids, one getExamsData(courseId, sequenceId) each, keeps response.exam || {}, and on any throw does logError(e) and keeps {}. Then dispatch(setExamsData(results)).
4. course-home/data/api.js — getExamsData GETs the LMS edx_proctoring attempt endpoint (or the edx-exams student/exam/attempt endpoint when EXAMS_BASE_URL is set), camelCases the body, and maps a 404 to {}.
5. course-home/data/slice.js — setExamsData stores the array at state.courseHome.examsData (initial null).

So the value a plugin reads is an array, positional with sectionScores's flattened subsection order, one entry per subsection, {} for subsections with no exam (or any fetch failure), otherwise the camelCased exam object; null until the first fetch resolves.

getExamsData hits the same two URLs as @edx/frontend-lib-special-exams' fetchExamAttemptsData (dist/data/api.js, v4.1.0). The library fetches one exam — the sequence rendered by SequenceExamWrapper — into its own specialExams slice; the progress tab needs attempt status for every subsection at once on a page that renders no exam, so #1829 re-implemented the fetch and fanned it out. If #2018 ends in a React Query conversion of the library, a follow-on could have the library export the query hook and the progress tab drop its copy.

What we established

• No in-repo reader. Deleting only the useGetExamsData(...) call in ProgressTab.jsx fails exactly the five tests in the Progress Tab › Exam data fetching integration block of ProgressTab.test.jsx (69 of 74 pass); every assertion in that block counts requests or inspects store.getState().courseHome.examsData directly. Nothing rendered changes.
• No visible external reader. A GitHub code search over the openedx org for examsData finds only this repo's tests and an unrelated instructor-dashboard file. Operator env.config.jsx files and fork-private plugins are not searchable, so absence there proves nothing — the fork cherry-pick is the evidence of use.
• Baseline probe. A local env.config.jsx inserting one DIRECT_PLUGIN widget into every progress-page slot, reading useSelector(state => state.courseHome.examsData), shows the identical array in all six slots that mount on the page (progress_tab_course_completion, progress_tab_certificate_status_main_body, progress_tab_course_grade, progress_tab_grade_breakdown, progress_tab_certificate_status_side_panel, progress_tab_related_links). The nested progress_certificate_status slot only mounts when a certificate card renders. Against the Tutor demo course every entry is {} (no proctored exams → every fetch is a 404); with a dev-only stub returning one exam per subsection, all six slots show the same 17-entry array.
• pluginProps are the slot contract, and examsData is not in any of them. The six slots pass enableProgressGraph (course completion) or nothing; the nested certificate slot passes courseId. The exam data was reachable only because plugins render inside the app's Redux Provider. Threading it through pluginProps would add it to six slots' contracts.

Decision

Replace the Redux path with an exported React Query hook that a plugin imports from learning's source. React Query dedupes by key, so the plugin's call and the progress tab's call share one fetch and no context provider is needed — the query cache does the job the Redux store did. The hook preserves the value shape a plugin sees today. The Redux read stops working, so the PR is marked breaking as #2016 was for the sidebar prefetch contract.