docs: user-facing Go strings and workflow input descriptions still teach `ksail cluster init`

[devantler]

🤖 Generated by the Daily AI Assistant

Part of #5626 (command-group taxonomy) — the residue #5644 deliberately left out of the prose sweep.

Problem

After #5644's prose repoint, the remaining places that still teach the deprecated ksail cluster init form (as the primary form, not as a deprecation note) are runtime strings and CI metadata, found by a repo-wide sweep:

• User-facing error/help strings in Go (these print to users at runtime): pkg/fsutil/validator/ksail/validator.go:498, pkg/fsutil/configmanager/talos/manager.go:175, pkg/svc/provisioner/cluster/factory_k3d.go:197,205, pkg/svc/registryresolver/oci.go:22.
• Workflow/action input descriptions: .github/workflows/system-test-omni.yaml, .github/workflows/system-test-hetzner.yaml, .github/actions/ksail-system-test/action.yaml, .github/actions/ksail-cluster/action.yml ("Run ksail cluster init before create").
• Code comments referencing the old form as primary (low priority; the deprecated-alias comments in cluster.go/cluster_test.go are correct and stay): scaffolder_kwok.go, k3d/helpers.go, ksail/distribution.go, eks/provisioner.go, local_service.go, gen_schema.go, clusterapi/local_service_test.go, chat/config_test.go (fixture strings).

Proposal

One small PR: repoint the runtime strings + workflow descriptions to ksail project init, regenerate anything derived (chat docs / snapshots that embed these strings — expect pkg/svc/chat/toolgen snapshot churn), and sweep the code comments in passing. Keep the deprecated-alias implementation comments as-is.

Acceptance criteria

• No runtime output or CI input description teaches ksail cluster init/ksail cluster add-environment as the primary form.
• Generated files regenerated, not hand-edited; full validate green.

Rough size: S.