modal_navigation_hint

Build the navigation hint for modals whose Tab keys move the cursor.

Only for screens where Tab and Shift+Tab step the selection. A modal that binds Tab to something else writes its own line rather than using this one -- mcp_viewer (Tab jumps between servers), model_selector (Tab autocompletes), and plugin_manager (Tab cycles tabs) all do.

The hint is long enough to wrap once a modal narrows, so the host Static needs height: auto to grow and dock: bottom to reserve the extra row. Without the dock the wrapped row is laid out past the modal's bottom edge, where the compositor never paints it.