remove separate ui service, serve ui with backend

src/routes/shutdown.rs

@@ -0,0 +1,8 @@
+use std::sync::mpsc;
+use tracing::{Level, event};
+
+#[allow(clippy::unused_async)]
+pub async fn shutdown(tx: mpsc::Sender<bool>) {
+    event!(Level::INFO, "Shutdown request received, stopping server...");
+    tx.send(true).expect("failed to send shutdown signal");
+}