[rodrigogs]

Summary

• synchronize the roving message-list state whenever an article receives DOM focus
• add a browser regression for direct focus followed by ArrowDown/ArrowUp navigation
• verify arrow keys remain owned by interactive controls inside messages
• run the regression in CI on an isolated strict port and ignore local Playwright output

Root cause

The message article could receive focus through Tab, click, script, or assistive technology without updating focusedMessageId. The next arrow key then navigated from stale state rather than from document.activeElement.

Verification

• RED: focused Playwright regression failed before the onfocus synchronization
• npm test — 29 files, 241 tests passed
• npm run check — 0 errors, 0 warnings
• npm run lint — passed
• npm run build — passed
• npm run test:global-search — passed, including privacy E2E
• npm run test:navigation:e2e — passed on Chromium with isolated --strictPort
• git diff --check origin/dev — passed

Follow-up hardening for #79.