Restore config loading, keep exported Version, keep cgo off

Bring back the in-progress viper and go-homedir configuration loading
from the original root command as a persistent pre-run on the root
command, with a --config flag and a config line in sutil info. Restore
the exported main.Version with a nolint directive instead of renaming
it. Export CGO_ENABLED=0 from the Makefile, drop -race from make test,
and remove the C toolchain from the Docker builder stage.

go.mod

@@ -4,15 +4,25 @@ go 1.26.0
 
 require (
 	github.com/kavfixnel/words v1.0.0
+	github.com/mitchellh/go-homedir v1.1.0
 	github.com/spf13/cobra v1.10.2
+	github.com/spf13/viper v1.21.0
 	github.com/stretchr/testify v1.12.1
 	github.com/tyler-smith/go-bip39 v1.1.0
 	golang.org/x/crypto v0.58.0
 )
 
 require (
+	github.com/fsnotify/fsnotify v1.9.0 // indirect
+	github.com/go-viper/mapstructure/v2 v2.4.0 // indirect
 	github.com/inconshreveable/mousetrap v1.1.0 // indirect
-	github.com/spf13/pflag v1.0.9 // indirect
+	github.com/pelletier/go-toml/v2 v2.2.4 // indirect
+	github.com/sagikazarmark/locafero v0.11.0 // indirect
+	github.com/sourcegraph/conc v0.3.1-0.20240121214520-5f936abd7ae8 // indirect
+	github.com/spf13/afero v1.15.0 // indirect
+	github.com/spf13/cast v1.10.0 // indirect
+	github.com/spf13/pflag v1.0.10 // indirect
+	github.com/subosito/gotenv v1.6.0 // indirect
 	go.yaml.in/yaml/v3 v3.0.5 // indirect
 	golang.org/x/sys v0.49.0 // indirect
 	golang.org/x/text v0.43.0 // indirect