Based on PR #1749 by @erosika (reimplemented on current main).
Extracts three protected methods from run() so wrapper CLIs can extend
the TUI without overriding the entire method:
- _get_extra_tui_widgets(): inject widgets between spacer and status bar
- _register_extra_tui_keybindings(kb, input_area): add keybindings
- _build_tui_layout_children(**widgets): full control over ordering
Default implementations reproduce existing layout exactly. The inline
HSplit in run() now delegates to _build_tui_layout_children().
5 tests covering defaults, widget insertion position, and keybinding
registration.
d70e07fc45