Returns a copy of the message with fragment tag literals escaped in its text content (string content,
and text / tool_result blocks) and toolCalls arguments. Returns the SAME object when nothing
needed escaping, so untouched messages keep their identity.
Returns a copy of the message with fragment tag literals escaped in its text content (string content, and
text/tool_resultblocks) and toolCalls arguments. Returns the SAME object when nothing needed escaping, so untouched messages keep their identity.