chore: scaffold axum server with in-memory CRUD, auth stub and tracing

backend/src/error.rs

@@ -0,0 +1,33 @@
+use std::fmt;
+
+use axum::{http::StatusCode, response::IntoResponse};
+use tracing::info;
+
+#[derive(Debug)]
+pub enum LoftError {
+    LoginFail,
+    FileIdNotFound,
+}
+
+impl fmt::Display for LoftError {
+    fn fmt(&self, f: &mut fmt::Formatter<'_>) -> fmt::Result {
+        write!(f, "{:?}", self)
+    }
+}
+
+impl std::error::Error for LoftError {}
+
+impl IntoResponse for LoftError {
+    fn into_response(self) -> axum::response::Response {
+        match self {
+            Self::LoginFail => {
+                info!("UNAUTHORIZED");
+                StatusCode::UNAUTHORIZED.into_response()
+            }
+            Self::FileIdNotFound => {
+                info!("NOT_FOUND");
+                StatusCode::NOT_FOUND.into_response()
+            }
+        }
+    }
+}