Localize the "message" and "attachment" role descriptions

[Eugene (OEvgeny)]

Screen readers announce messages and attachments as "message" and "attachment" in English, whatever the locale.

Changelog Entry

Fixed

• Fixed the "message" and "attachment" role descriptions being hard-coded in English, in PR #5916, by @OEvgeny

Description

The aria-roledescription of the message and attachment groups in stacked and carousel layouts was hard-coded in English. They now come from 2 new localized strings, which hosts can also set via overrideLocalizedStrings until translations arrive.

Design

• New strings ACTIVITY_MESSAGE_ARIA_ROLE_ALT and ACTIVITY_ATTACHMENT_ARIA_ROLE_ALT, named like TRANSCRIPT_ARIA_ROLE_ALT; no existing string fits.
• Overlaps Announce each message with its own bot initials and, on arrow keys, its time #5898, which removes localize from CarouselFilmStrip and StackedLayoutInner: git merges either order cleanly, so the PR merged second must keep const localize = useLocalizer() in both (ESLint/tsc flag it otherwise).

Specific Changes

• en-US.json: added the 2 strings with comments

• StackedLayout.tsx, AttachmentRow.tsx, CarouselFilmStrip.js, CarouselFilmStripAttachment.js: localize aria-roledescription

• Added accessibility/aria-roledescription.localized.html: asserts "message"/"attachment" in en-US, then "Nachricht"/"Anhang" with German overrides; snapshots 1–2 show the stacked and carousel messages and the live region copy, in English then German

• I have added tests and executed them locally

• I have updated CHANGELOG.md

• I have updated documentation

Review Checklist

This section is for contributors to review your work.

• Accessibility reviewed (tab order, content readability, alt text, color contrast)
• Browser and platform compatibilities reviewed
• CSS styles reviewed (minimal rules, no z-index)
• Documents reviewed (docs, samples, live demo)
• Internationalization reviewed (strings, unit formatting)
• package.json and package-lock.json reviewed
• Security reviewed (no data URIs, check for nonce leak)
• Tests reviewed (coverage, legitimacy)

[Eugene (OEvgeny)]

[Eugene (OEvgeny)]

TODO: show announced activities by applying styles to live region and taking snapshot

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