style: clear pre-existing lint and gofmt debt

[james-nesbitt]

What

Clear pre-existing lint and gofmt debt on main. No functional changes.

Why

make lint currently fails on main with 5 issues, and three files are not gofmt-clean. This is unrelated to any feature work — it just means anyone running make lint locally starts from a red baseline, and new violations are easy to miss in the noise.

How

golangci-lint (5 → 0 issues):

• pkg/product/mke/config/cluster_spec.go — double blank line in UnmarshalYAML (gci)
• pkg/product/mke/config/host.go — formatting (gci)
• pkg/configurer/windows.go — stray blank line after the InstallMCR opening brace (gofumpt, whitespace); leftover from [PRODENG-3471] Fix Windows MCR install failing on FIPS channels #640 removing version := "latest"
• pkg/docker/image.go — rename wp → pool (varnamelen). Deliberately matches the name already used on the rig v2 migration branch, so that rebase stays clean.

gofmt (not covered by make lint, which sets run.tests: false):

• pkg/product/mke/phase/validate_facts_test.go, test/platforms.go, test/smoke/smoke_test.go — struct field alignment and one trailing blank line

Everything except the wp → pool rename was applied by golangci-lint run --fix / gofmt -w; the rename was done via LSP so all three references moved together.

Testing

• make lint → 0 issues
• gofmt -l across ./pkg ./cmd ./test . → clean
• go build ./..., go vet ./..., and go vet -tags=integration ./test/... all pass
• go test ./pkg/... passes

Links

• JIRA: N/A (pure lint/format hygiene, no ticket)

Checklist

• Tests added or updated (N/A — formatting only, no behaviour change)
• Docs updated if user-visible behaviour changed (N/A)
• No debug output or dead code left in

Written by AI: claude-sonnet-5