chore(example): use the current logger API in the standalone example

[juicycleff]

The standalone example still constructs its logger with
log.NewBeautifulLogger, which go-utils v1.3.0 keeps working as a deprecated
shim. An example is the wrong place to demonstrate a deprecated constructor.

- logger := log.NewBeautifulLogger("authsome")
+ logger := log.New(log.Config{Name: "authsome"})

Behaviour is identical. The added comment records what that behaviour is, since
it is no longer implied by the constructor's name: the format is chosen from the
output, a terminal getting aligned coloured columns and anything else JSON, with
FORGE_LOG_FORMAT overriding both.

One line plus its comment. This is the last piece of the go-utils v1.3.0
adoption — the version bumps are already on main via 2ceff13, and #108 was
closed as stale once those landed.

Heads up: ci / Lint is red on main, unrelated to this

golangci-lint reports 6 findings on current main, none of them in
_examples. Verified by stashing this change and re-running: the same 6 appear.

middleware/client_autorefresh_test.go  bodyclose ×3, noctx, unparam
sdk/go/client_refresh.go               errcheck

They came in with c472f0b fix: fixed the client refresh, after #109 cleared
the retention findings. Happy to fix them in a follow-up in the same shape as
#109 — say the word.