go-1-27

Go 1.27 ships `encoding/json/v2` in the standard library and quietly re-implements the old `encoding/json` package on top of it, changing error strings and flipping defaults such as nil slices becoming `[]`, case-sensitive field matching, duplicate key rejection, and `time.Duration` no longer marshaling when v2 is imported directly.

A hands-on interactive tour of Go 1.27's new features, highlighting generic methods, struct literal field selectors, and more, with runnable examples based on the official release notes.