You didn’t pass any context to the partial.
In themes/three4th/layouts/_default/baseof.html, change this:
{{- partial "footer.html"}}
to this:
{{- partial "footer.html" . }}
Alternatively, since the footer currently doesn’t require access to anything other than site variables, you could use the site
function instead of accessing the site variables via context. Change this:
{{- range .Site.Params.link }}
to this:
{{- range site.Params.link }}