Migrate the deprecated gofumpt `extra-rules` to `extra.group-params`, as
the alias now also enables the new `clothe-returns` and `balance-calls`
rules. Disable SA4023, which hangs on go 1.27, see
https://github.com/golangci/golangci-lint/issues/6732.
Apply the resulting modernize fixes, mostly flattening embedded struct
literals and switching errors.As to errors.AsType.
Assisted-by: Claude:Opus 5