rename frontend to app

src/main.rs

@@ -1,10 +1,10 @@
-use frontend::App;
+use app::App;
 use joecalsend::{Config, error, models::Device};
 use local_ip_address::local_ip;
 use network_interface::{Addr, NetworkInterface, NetworkInterfaceConfig, V4IfAddr};
 use tui_logger::{LevelFilter, init_logger, set_env_filter_from_env};
 
-mod frontend;
+mod app;
 
 fn main() -> error::Result<()> {
     let device = Device::default();