One Go binary with a subcommand per former script, invoked as
'go run ./scripts/newsletter <command>' from repo root. Stdlib only;
publications config embedded via go:embed (go run recompiles on edit).
Behavior parity verified side-by-side before deleting the JS —
see plans/reports/parity-260818-newsletter-go-migration-report.md.
Permissions: allow 'Bash(go *)', drop 'Bash(node *)' and the redundant
'Write(content)' rule (Edit rules cover all file-editing tools).
