A new Go API for JSON

Go 1.27 adds two stable packages, encoding/json/v2 and encoding/json/jsontext, after an experiment announced last year. The redesign fixes long-standing issues in the original encoding/json, including acceptance of invalid UTF-8 and objects with duplicate member names. For developers, the new defaults mean stricter, safer parsing of JSON data, so code that depends on lenient behavior may need review when upgrading.