peerpod-ctrl: register gcp cloud provider

[PeteE]

Summary

• Adds src/peerpod-ctrl/controllers/gcp.go, a //go:build gcp blank import of cloud-providers/gcp, mirroring the existing aws.go / azure.go / libvirt.go / ibmcloud.go / alibabacloud.go / byom.go registration files in the same package.
• Without this, building peerpod-ctrl with -tags gcp compiles successfully but the GCP cloud-provider's init() is never linked in, so cloud.GetProvider("gcp") returns nothing and peerpod-ctrl cannot delete peer-pod VMs on GCP.
• go.mod / go.sum changes are produced by go mod tidy after adding the import — every new entry carries // indirect because peerpod-ctrl only reaches the GCP SDK transitively through the cloud-providers/gcp package.

Motivation

Observed in a live GKE cluster running peerpod-ctrl built with -tags gcp. When a peer-pod is torn down, the reconciler logs:

INFO  deleting instance  {"InstanceID":"podvm-nginx-77b895b97f-xm8j5-b7bfc5f6","CloudProvider":"gcp"}
2026/05/19 16:18:26 [adaptor/cloud] Cloud provider external plugin loading is disabled, skipping plugin loading
ERROR Reconciler error  {"error":"gcp cloud provider not supported"}
sigs.k8s.io/controller-runtime/pkg/internal/controller.(*Controller[...]).reconcileHandler
    /go/pkg/mod/sigs.k8s.io/controller-runtime@v0.23.1/pkg/internal/controller/controller.go:495

"gcp cloud provider not supported" is the error returned when the provider registry has no gcp entry. With this blank import in place under the gcp build tag, the registry is populated and the reconciler succeeds.

Test plan

• go build -tags gcp ./... in src/peerpod-ctrl/ succeeds
• go mod tidy produces no further changes after the import is added
• Deploy peerpod-ctrl built with -tags gcp on GKE, delete a peer-pod, confirm the reconciler no longer returns gcp cloud provider not supported

🤖 Generated with Claude Code

[bpradipt]

/lgtm
Thanks @PeteE

[snir911]

Thanks! LGTM, @PeteEC can you confirm this was tested? (run pod -> delete caa -> delete pod -> pod is dangling -> peerpod-ctrl clean the dangling pod)

[PeteE]

Thanks! LGTM, @PeteEC can you confirm this was tested? (run pod -> delete caa -> delete pod -> pod is dangling -> peerpod-ctrl clean the dangling pod)

Yes I will verify today and post results!

[bpradipt]

Thanks! LGTM, @PeteEC can you confirm this was tested? (run pod -> delete caa -> delete pod -> pod is dangling -> peerpod-ctrl clean the dangling pod)

Yes I will verify today and post results!

@PeteE possible to post the result today and rebase it?

[beraldoleal]

LGTM, thanks. Needs a rebase tho.