add : all folder + files for backend project

backend/src/main.rs

@@ -0,0 +1,14 @@
+use axum::{routing::get, Router};
+use std::net::SocketAddr;
+
+#[tokio::main]
+async fn main() {
+    let app = Router::new().route("/", get(|| async { "Hello, world!" }));
+
+    let addr = SocketAddr::from(([127, 0, 0, 1], 3000));
+    println!("listening on {}", addr);
+    axum_server::bind(addr)
+        .serve(app.into_make_service())
+        .await
+        .unwrap();
+}