Screen-reader / plain-render mode for the TUI

What feature would you like to see?

Menus already render a ❯ text marker (not color-only), but pi-tui's differential redraw makes position changes invisible to screen readers. The bundled web UI already ships ARIA markup — the terminal UI has no equivalent path.

In other words, blind people cannot tell where the cursor is positioned.

Suggestions:

1. An env var / tui.toml flag (e.g. accessibility = true) that switches rendering to append-only linear output: no alternate screen, no differential in-place redraws — every state change is printed as a new line.
2. In menus, announce selection changes as a printed line (e.g. re-print ❯ <label> on each arrow-key move), so screen readers speak the new position.
3. Extend the approval panel's number-key direct selection (1–9) to all pickers (/model, /theme, /settings, session/task pickers).
4. Document the mode on an accessibility docs page.

Happy to test or contribute with a PR, not sure yet what the policies are. I'm 30 minutes into Kimi Code and loving it!

Additional information

No response

No file or test is named. Start by locating the TUI's differential redraw and alternate-screen handling, then trace the approval panel and the /model, /theme, /settings, and session/task pickers. Done should include a selectable linear mode, spoken selection changes, number-key selection across pickers, and an accessibility documentation page.