feat(tui): adopt an asynchronous Tokio runtime for the TUI frontend

Refactor TUI event handling and rendering to improve responsiveness and use a unified managed client worker.

crates/irtt-app/src/signal.rs

@@ -1,18 +1,18 @@
-#[cfg(any(feature = "server", feature = "tui"))]
+#[cfg(feature = "server")]
 use std::sync::{
     atomic::{AtomicBool, Ordering},
     Arc,
 };
 
-#[cfg(any(feature = "server", feature = "tui"))]
+#[cfg(feature = "server")]
 pub fn install_signal_handler(shutdown_requested: Arc<AtomicBool>) -> Result<(), ctrlc::Error> {
     ctrlc::set_handler(move || {
         shutdown_requested.store(true, Ordering::Relaxed);
     })
 }
 
-/// Preserve ctrlc's SIGINT/SIGTERM policy while waking the async client.
-#[cfg(feature = "client")]
+/// Preserve ctrlc's SIGINT/SIGTERM policy while waking the async frontends.
+#[cfg(any(feature = "client", feature = "tui"))]
 pub fn install_async_signal_handler() -> Result<tokio::sync::watch::Receiver<bool>, ctrlc::Error> {
     let (shutdown, receiver) = tokio::sync::watch::channel(false);
     ctrlc::set_handler(move || {