feat: Enhance error handling by adding Forbidden and Unknown error types

libertas_core/src/error.rs

@@ -23,6 +23,9 @@ pub enum CoreError {
     #[error("Authentication failed: {0}")]
     Auth(String),
 
+    #[error("Forbidden: {0}")]
+    Forbidden(String),
+
     #[error("An unknown error occurred: {0}")]
     Unknown(String),
 }