Refactor App to use unified AppChannels for events

App now receives an AppChannels struct; AppEvent enum removed.

Event handling, tick generation, and audio communication are now
performed through dedicated channels.

src/app/threads/tick.rs

@@ -1,22 +1,19 @@
-use crate::app::threads::AppEvent;
 use std::{
     sync::mpsc::Sender,
     thread,
     time::{Duration, Instant},
 };
 
-pub fn spawn_tick_thread(tx: Sender<AppEvent>, interval_ms: u64) {
-    thread::spawn(move || {
-        let interval: Duration = Duration::from_millis(interval_ms);
-        loop {
-            if tx.send(AppEvent::Tick).is_err() {
-                break;
-            }
-
-            let elapsed: Duration = Instant::now().elapsed();
-            if interval > elapsed {
-                thread::sleep(interval - elapsed);
-            }
+pub fn handle_tick_event(tx: Sender<()>, interval_ms: u8) {
+    let interval: Duration = Duration::from_millis(interval_ms as u64);
+    loop {
+        if tx.send(()).is_err() {
+            break;
         }
-    });
+
+        let elapsed: Duration = Instant::now().elapsed();
+        if interval > elapsed {
+            thread::sleep(interval - elapsed);
+        }
+    }
 }