feat: account dispute emails

mail/render.go

@@ -69,17 +69,21 @@ func perRender(hq, tone string) map[string]any {
 // The subject comes from the text set, not the HTML one: html/template would
 // escape an ampersand in an instance name into "&" and mail clients show
 // subjects verbatim.
-func render(name string, data any, hq string) (message, error) {
+func render(name string, data any, hq ...string) (message, error) {
 	s, ok := sets[name]
 	if !ok {
 		return message{}, fmt.Errorf("no such template")
 	}
+	var hqURL string
+	if len(hq) > 0 {
+		hqURL = hq[0]
+	}
 
 	var tone strings.Builder
 	if err := s.text.ExecuteTemplate(&tone, "tone", data); err != nil {
 		return message{}, err
 	}
-	per := perRender(hq, strings.TrimSpace(tone.String()))
+	per := perRender(hqURL, strings.TrimSpace(tone.String()))
 
 	ht, err := s.html.Clone()
 	if err != nil {