DC-477 - prevent double-submit on enrollment checker review page

[necampanini]

🔗 Jira ticket

DC-477

✍️ Description

Prevents double submission on the enrollment checker review page. A fast double-click on Submit could fire the check twice: the isSubmitting state flag isn't updated until React's next render, so both click handlers ran against the stale false value and both passed the guard. A synchronous useRef guard now rejects the second click immediately. The Submit button shows a loading state and the Back button is disabled while the request is in flight.

🔗 Links to related PRs

• none

✅ Completion tasks

• Added relevant tests
• Meets acceptance criteria in ticket
• Configuration changes:
  • If new environment variables are added, update in Tofu
  • If new environment secrets are added, update in Tofu and set in AWS Secret Manager
  • If you're adding an appsetting, add it to the requisite example file, and update it in the AWS AppConfig
  • If appsetttings are changed, update in AWS AppConfig

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Priority Review Table

Priority	File	Unit	Sec	Cpx	Nov	Notes
🟡	src/SEBT.EnrollmentChecker.Web/src/app/review/page.tsx	handleSubmit() + submittingRef	Low	Med	Med	sync guard blocks double-submit
🟢	src/SEBT.EnrollmentChecker.Web/src/features/enrollment/components/ReviewPage.tsx	isSubmitting prop wiring	Low	Low	Low
🟢	src/SEBT.EnrollmentChecker.Web/src/app/review/page.test.tsx	new tests	Low	Low	Low
🟢	src/SEBT.EnrollmentChecker.Web/src/features/enrollment/components/ReviewPage.test.tsx	updated tests	Low	Low	Low

[noxmwalsh]

Does it make sense to disable this too along with the "Back" and "Submit" button. Maybe that's a product call, but I feel like it would make sense.

[noxmwalsh]

Approved with comments regarding disabling additional buttons