Remove dead code in hugo/helpers.go (unused image-rewrite helpers)

[patrick-hermann-sva]

Summary

hugo/helpers.go contains four unexported functions that are never called anywhere in the hugo module:

• extractImageLinks (helpers.go:14)
• downloadImages (helpers.go:28)
• replaceImageLinks (helpers.go:60)
• downloadImageAsBytes (helpers.go:75)

All four have zero call sites (verified by grep across hugo/**/*.go, excluding their own definitions). They appear to be image-link rewriting helpers that were never wired into an exported module function (last touched in 309376b feat: fix/update-hugo-img-rewrites).

Why it isn't already failing lint

The repo's golangci-lint runs with only-new-issues: true, so the pre-existing unused findings are grandfathered and never reported. This was surfaced in #308: re-applying a refactor from the stale #152 touched these lines, which made golangci-lint flag them as new unused/errcheck issues — at which point it became clear the whole file is dead.

Proposed action

Either:

1. Delete hugo/helpers.go if the image-rewrite feature is not planned, or
2. Wire the helpers into the intended exported function if the feature was meant to ship.

Option 1 is the likely answer; confirm with whoever authored the img-rewrite work.

Notes

• These are unexported funcs, so removing them is not a breaking change to module consumers.
• Pure cleanup — chore:/refactor: scope, no release impact.

Filed as follow-up to #308 (which salvaged the still-relevant parts of the now-closed #152).