[A11y] 4.1.2 Name, Role, Value – 'Disclosure triangle' announced on expandable sections

Split from #381, which reported five separate problems under one ticket.

Tester has observed that on Android TalkBack, "disclosure triangle" is announced when the user navigates to the expandable sections.

This does not comply with WCAG Level A 2.2:
4.1.2 Name, Role, Value - https://www.w3.org/WAI/WCAG22/Understanding/name-role-value.html

Steps to Recreate:

1. Navigate to URL
2. Navigate to an expandable section with Android TalkBack enabled
3. Observe issue

This has been observed on the following pages:

• Guidance
• Permanent Exclusion

Environment:
Android 15 - Samsung Galaxy S22 - Chrome 151 - TalkBack (mobile screen reader)

Reproduction rate:
100% - Consistently reproducible.

Supporting material:
Video: https://drive.google.com/drive/folders/1Ph21Q5-UlnfnvKJ1zQQA-K5uM-WY14X2?usp=sharing

Version: https://check-performance-data-preproduction.teacherservices.cloud/

2.Major Impact on Accessibility

Assessment needed before any work. The expandable sections use the native HTML <details> / <summary> elements (the GOV.UK Details component, Views/Journey/_Question.cshtml). "Disclosure triangle" is TalkBack's own name for that native role, not text this service supplies. This may well be a "no action" outcome. Confirm with the auditor before changing the markup, because replacing the native element with ARIA is usually worse for other assistive technology.

Priority: High
DoneDone issue: https://zoonou.mydonedone.com/issuetracker/projects/91343/issues/8

Parent: #373. Split from: #381

Start with Views/Journey/_Question.cshtml and the GOV.UK Details component used for the expandable sections. Reproduce the announcement on the Guidance and Permanent Exclusion pages with Android TalkBack, then confirm the expected behavior with the auditor before changing markup. Done means the auditor agrees on either no action or a specific accessible outcome.