a11y: audit non-files surfaces (modals, lifecycle buttons, flash, console) for role/aria-live

[AbstractNucleus]

What: Recent ARIA work landed for the file tree (#84). Other surfaces (modals, lifecycle buttons, flash messages, console) likely lack role / aria-live / focus management.

Why: Keyboard-only and screen-reader users currently get a degraded experience on every non-files surface.

Approach: Audit each interactive surface against WAI-ARIA APG patterns: modal dialogs need role="dialog" + focus trap, flash messages need aria-live="polite", lifecycle button group needs proper labelling. File one PR per surface.

[AbstractNucleus]

This was generated by AI during triage.

Routed to ready-for-human — verifying a11y fixes requires hands-on testing with a screen reader (NVDA/VoiceOver) and keyboard-only flows. Automated checks (axe, Lighthouse) catch a fraction; the rest is judgment.

Each surface (modal, lifecycle buttons, flash, console) could become its own ready-for-agent issue once the per-surface acceptance criteria are nailed down by hand.