Extends `X-Idempotency-Key` header usage to `DELETE` and `PUT` requests, ensuring idempotent behavior for a wider range of modifying API operations. Updates the documentation and client implementation for `DELETE` requests.
Refactors `handleResponse` to robustly parse API responses. It now reads the response body once as text, enabling graceful handling of non-JSON error bodies and consistent processing of successful or empty responses.
