Join input thread before exiting

Store the input event thread handle and join it after the app finishes.
This
replaces the previous fire‑and‑forget spawn and ensures the thread is
cleanly
terminated before the program exits.

src/main.rs

@@ -2,7 +2,7 @@ use ratatui::{Terminal, prelude::CrosstermBackend};
 use std::{
     io::{Result, Stdout},
     sync::mpsc::{Sender, channel},
-    thread,
+    thread::{self, JoinHandle},
 };
 use war_in_tunnels::{
     app::{App, AppEvent, handle_input_events},
@@ -27,12 +27,14 @@ fn main() -> Result<()> {
     let (event_tx, event_rx) = channel::<AppEvent>();
 
     let tx_to_input_events: Sender<AppEvent> = event_tx.clone();
-    thread::spawn(move || {
+    let input_thread: JoinHandle<()> = thread::spawn(move || {
         handle_input_events(tx_to_input_events);
     });
 
     let app_result: Result<()> = app.run(&mut terminal, event_rx);
     ratatui::restore();
 
+    let _ = input_thread.join();
+
     app_result
 }