Add version command

[adamancini]

Summary

• Adds version subcommand to display sbctl version and Go compiler version
• Updates Makefile to set version during build time
• Updates README with version command documentation

Test plan

1. Build the binary with \go mod tidy
   go fmt ./pkg/... ./cli/... ./tests/...
   go vet -tags "netgo containers_image_ostree_stub exclude_graphdriver_devicemapper exclude_graphdriver_btrfs containers_image_openpgp" -installsuffix netgo ./pkg/... ./cli/... ./tests/...
   go build -o bin/sbctl -ldflags "-X github.com/replicatedhq/sbctl/cli.Version=v0.17.1-33-gadd33d0" sbctl.go
2. Run \v0.17.1-33-gadd33d0
   go1.24.2 to verify it displays both the sbctl version and Go compiler version

[banjoh]

I'd prepend sbctl to the version string. Something like below

sbctl version v0.17.1-33-gadd33d0
go version go1.24.2

Somehow I got back to this to review before I saw Evan's comment. I agree adding the Go version would also be helpful

[scottrigby]

Please ignore all the noise above. Wish I could hide my stale review reason. Anyway, moving along here…

I'd prepend sbctl to the version string. Something like below

sbctl version v0.17.1-33-gadd33d0
go version go1.24.2

@banjoh thinking about it slightly more… at risk of bikeshedding, I like the output as-is:

$ ./bin/sbctl version
v0.17.1-33-gadd33d0
go1.23.8

I think it's clear the first line is the command version, and go version already has go prepended.
Either would be fine, just thought I'd share my thoughts.

[adamancini]

@banjoh @scottrigby I don't have any objections to either, for reference the replicated CLI looks like this:

 ✔  AdaM-GK2GXPC49X  ~/go/src/github.com/replicatedhq  replicated version
replicated version 0.101.1

[adamancini]

@banjoh ready for re-review:

 ./bin/sbctl version           
sbctl version v0.17.1-33-gadd33d0
go version go1.24.2