Add Go workflow for fix, fmt, test, lint, and screenshot update

[arran4]

This PR adds a GitHub Actions workflow to run go fix, fmt, vet, test, golangci-lint, and regenerate the screenshot. If changes are detected, it creates a PR and fails the workflow.
The PR also includes the fixes from go fix and go fmt to ensure the workflow passes.

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PR created automatically by Jules for task 16464188690140872075 started by @arran4

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