Upgrade TUI stack: ratatui 0.30, crossterm 0.29

Constrain run_app backend to Error = io::Error for ratatui 0.30's
associated backend error type.

Co-Authored-By: Claude Fable 5 <noreply@anthropic.com>

src/events.rs

@@ -10,7 +10,7 @@ use crate::app::{App, ConfirmAction, ContextMenuItem, DialogMode, Focus, Setting
 use crate::config::{AppliesTo, CustomMenuItem};
 use crate::ui;
 
-pub fn run_app<B: Backend>(terminal: &mut Terminal<B>, app: &mut App) -> io::Result<()> {
+pub fn run_app<B: Backend<Error = io::Error>>(terminal: &mut Terminal<B>, app: &mut App) -> io::Result<()> {
     loop {
         terminal.draw(|f| ui::draw(f, app))?;