Sign up/in/out and authentication.

backend/src/user.rs

@@ -0,0 +1,11 @@
+use chrono::prelude::*;
+
+pub struct User {
+
+}
+
+pub struct UserLoginInfo {
+    pub last_login_datetime: DateTime<Utc>,
+    pub ip: String,
+    pub user_agent: String,
+}