Drop JoinHandle variables and thread joins

Thread handles are no longer kept; spawn threads directly and omit the
join calls. The unused `JoinHandle` import and related comments are
removed.

src/main.rs

@@ -3,7 +3,7 @@ use std::{
     io::{Result, Stdout},
     mem::replace,
     sync::mpsc::{Receiver, Sender, channel},
-    thread::{self, JoinHandle},
+    thread,
 };
 use war_in_tunnels::{
     app::{
@@ -27,14 +27,12 @@ fn main() -> Result<()> {
 
     let input_tx: Sender<KeyEvent> = channels.input_tx.clone();
     let resize_tx: Sender<(u16, u16)> = channels.resize_tx.clone();
-    let events_thread: JoinHandle<()> =
     thread::spawn(move || handle_ct_events(input_tx, resize_tx));
 
     let tick_tx: Sender<()> = channels.tick_tx.clone();
-    let tick_thread: JoinHandle<()> = thread::spawn(move || handle_tick_event(tick_tx, TICK_MS));
+    thread::spawn(move || handle_tick_event(tick_tx, TICK_MS));
 
     let audio_rx: Receiver<AudioCmd> = replace(&mut channels.audio_rx, channel().1);
-    // let audio_thread: JoinHandle<()> =
     thread::spawn(move || {
         handle_audio(audio_rx, args.mute, args.sound_track);
     });
@@ -46,9 +44,5 @@ fn main() -> Result<()> {
 
     ratatui::restore();
 
-    let _ = events_thread.join();
-    let _ = tick_thread.join();
-    // let _ = audio_thread.join(); // TODO: kill playing music
-
     app_result
 }