Module message 

JMAP Chat — Message/* method implementations on SessionClient.

Each method follows the standard five-step pattern:

1. Validate arguments (defence-in-depth empty-state guards).
2. Call self.session_parts()? → (api_url, account_id).
3. Build args JSON with serde_json::json!({…}).
4. Call build_request(method_name, args, USING_CHAT).
5. Call self.call_internal(api_url, &req).await?.
6. Call jmap_base_client::extract_response(&resp, CALL_ID)?.

SPECIAL: message_create additionally inspects SetResponse.not_created for error_type == "rateLimited" and surfaces it as ClientError::RateLimited.