feat(blog): add "What's New in Go 1.27" post

Covers the Go 1.27 release: generic methods, struct literal field
selectors, generalized function type inference, encoding/json/v2,
the new uuid and crypto/mldsa packages, the goroutine leak profile,
and the toolchain changes.

All code examples and their outputs were executed against go1.27rc3
on darwin/arm64 rather than transcribed from the release notes.

Co-Authored-By: Claude Opus 5 (1M context) <noreply@anthropic.com>

Author: iwanhae