Adds descriptive aria-labels to thread titles allowing users to navigate
and open threads via keyboard, improving screen reader experience.

refactor: improve accessibility for duo-chat multi-threaded

See merge request !70

Add sr-only text `Me:` before messages from user and `Duo:` before
messages from Duo.

fix: Add accessible sender context for Duo Chat messages

See merge request !71

## [8.7.2](v8.7.1...v8.7.2) (2025-03-13)

### Bug Fixes

* Add accessible sender context for Duo Chat messages ([68d60347](68d60347))