refactor: convert the requestCert writer to a React Query mutation

[brian-smith-tcril]

Summary

Convert the shared requestCert POST thunk to a useRequestCert React Query mutation and delete the thunk. Part of the Redux → React Query migration (#1946). Prerequisite below the outline-tab conversion (#1991) — outline's CertificateStatusAlert is one of this thunk's three callers, so converting requestCert first lets outline build on an already-converted base. Closes #1994.

requestCert is a fire-and-forget "request certificate" POST (postRequestCert → /courses/{courseId}/generate_user_cert) shared by three tabs, so all three callers convert together — the only way to delete the thunk rather than leave a redundant POST path.

What changed

• apiHooks.ts — add useRequestCert (mutationFn: ({ courseId }) => postRequestCert(courseId), onError: logError), mirroring the other course-home mutations.
• Convert the three callers from dispatch(requestCert(courseId)) to useRequestCert().mutate({ courseId }), dropping each file's useDispatch + requestCert thunk import:
  • course-home/outline-tab/alerts/certificate-status-alert/CertificateStatusAlert.jsx
  • courseware/course/course-exit/CourseCelebration.jsx
  • course-home/progress-tab/certificate-status/CertificateStatus.jsx
• data/thunks.js — delete the requestCert thunk and its now-unused postRequestCert import. (requestCert isn't re-exported from data/index.js, so no re-export change.)

Behavior

No user-facing change. The thunk and the mutation both call the same postRequestCert(courseId) → identical fire-and-forget POST, no response handling. The only delta is onError: logError (the thunk left failures unhandled) — a strict improvement.

Testing

npm run types, npm run lint, and the full npm test suite (106 suites, 3 pre-existing skips) pass. New useRequestCert coverage in apiHooks.test.tsx (asserts the POST + error logging). All three callers' click paths are now exercised: ProgressTab.test.jsx and CourseExit.test.jsx click the request-certificate button and assert the generate_user_cert POST fires; OutlineTab.test.jsx already clicks it. (The CourseExit click test was added here — its button previously rendered but was never clicked, leaving the mutate line uncovered.)

Decisions

Full decision log

Decisions — convert the requestCert writer to a React Query mutation (#1994)

Working notes for this PR (part of the Redux → React Query migration, #1946).
Not checked in. A prerequisite below the outline-tab conversion (#1991).

Whole-writer conversion, not per-tab

Decision. Convert requestCert across all three of its callers in one
PR and delete the thunk, rather than converting per-tab:

• outline-tab/.../CertificateStatusAlert.jsx (outline)
• courseware/course/course-exit/CourseCelebration.jsx (course-exit)
• progress-tab/certificate-status/CertificateStatus.jsx (progress)

Why. requestCert is a single shared thunk with three callers. To actually
delete the thunk (not just relocate a redundant POST path), every caller must
stop using it. This surfaced while converting the outline tab (#1991): deleting
the thunk there would have broken course-exit and progress, which also dispatch
it.

Its own layer, below outline

Decision. requestCert converts in a dedicated layer beneath the
outline-tab conversion (#1991), not folded into it.

Why. Outline's CertificateStatusAlert is one of the three callers. Landing
the writer conversion below outline lets the outline PR build on an
already-converted CertificateStatusAlert and keeps a shared-code change out of
the tab-conversion diff. (dismissWelcomeMessage, which is genuinely
outline-only, stays in the outline PR.)

Behavior-preserving

Decision. useRequestCert is a fire-and-forget mutation calling the same
postRequestCert(courseId) the thunk did; onError: logError is the only delta.

Why. Both paths POST to /courses/{courseId}/generate_user_cert with no
response handling. The thunk left failures unhandled; the mutation logs them — a
strict improvement, no user-facing change.

🤖 Generated with Claude Code

[codecov]

Codecov Report

✅ All modified and coverable lines are covered by tests.
✅ Project coverage is 92.96%. Comparing base (2d7d34e) to head (82889d7).

Additional details and impacted files

@@                            Coverage Diff                             @@
##           bsmith/react-query-tour-button-cleanup    #1995      +/-   ##
==========================================================================
+ Coverage                                   92.87%   92.96%   +0.08%     
==========================================================================
  Files                                         363      363              
  Lines                                        5938     5939       +1     
  Branches                                     1381     1381              
==========================================================================
+ Hits                                         5515     5521       +6     
+ Misses                                        403      399       -4     
+ Partials                                       20       19       -1     

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