[Fix] Session cards trigger an accessibility audit violation on actor avatars

[roomote-roomote]

​Opened on behalf of @daniel-lxs. Follow up by mentioning @roomote-roomote, in the web UI, or in Telegram.

Related issue

Not applicable: this is an internally authorized accessibility fix.

Why this PR exists

• A maintainer explicitly invited this PR in the linked issue or discussion
• I am a maintainer / this is internal Roomote work

What changed

Session cards now keep actor avatars decorative when the adjacent actor text already names the session owner. User avatars use the existing empty-alt convention, and automation avatars are hidden from the accessibility tree instead of exposing an invalid label on a generic element. The visible avatar layout and actor text are unchanged, while screen readers receive one actor announcement from the existing card metadata.

How it was tested

• Added focused SessionCard coverage for user and automation avatar semantics; the focused suite passes 14/14.
• The full @roomote/web client suite passes 329 files and 3007 tests.
• @roomote/web typecheck, lint, and format checks pass; pnpm lint:pre-push passes oxlint, residual lint, 27-package fast typechecks, and Knip.
• Authenticated local /sessions reproduction dropped the serious aria-prohibited-attr violation on 7 avatar nodes; targeted card axe checks show no instance of that rule, and the accessibility tree keeps the actor text without an avatar announcement.
• The original visual-proof handoff timed out. The follow-up validation below resolves that gap; this PR is non-draft.

Checklist

• The PR title follows the repo convention: [Fix], [Feat], [Improve], [Refactor], [Docs], or [Chore] followed by a user-facing description
• This PR is small and scoped to one change
• pnpm lint and pnpm check-types pass locally
• I added tests or included a clear manual validation note above
• I removed secrets, tokens, private keys, and customer data from code, logs, and screenshots
• If this change should appear in the changelog, I ran pnpm changeset

Follow-up validation

Fresh authenticated product checks on unchanged head 9553899f compared current develop with this PR using loaded-image, missing-image fallback, automation-owned, and current-viewer avatar cards. The avatar labels disappear from the accessibility tree while the adjacent actor text, unread indicator, card links, and action controls remain available. Desktop and 390×844 mobile layouts were inspected; all four card dimensions matched the baseline and keyboard activation still opened the correct session.

All 23 focused SessionCard and Avatar tests, web fast typechecking, scoped lint, and formatting passed. This follow-up inspected rendered DOM and browser accessibility semantics; it does not claim a new full-page axe audit or screen-reader audio test.

Screenshots

Original author captures, recovered and visually inspected as references alongside the fresh local validation above. These are not captures of the additional follow-up fixtures.

[roomote-community]

No code issues found. See task

_{Reviewed 9553899}

[daniel-lxs]

Verified the exact head against current develop using loaded-image, missing-image fallback, automation-owned, and current-viewer avatar states. Redundant avatar labels disappear from the browser accessibility tree while adjacent actor text, unread indicators, and card controls remain available. Desktop/mobile card geometry is unchanged and keyboard navigation still works. All 23 focused SessionCard/Avatar tests, web typecheck, scoped lint, and formatting passed.