chore: migrate mail themes to shared framework and locked upstream inputs

tools/preview/funcs.go

@@ -9,9 +9,11 @@ import (
 
 // TemplateFuncs maps Gitea's built-in template functions available in mail templates.
 var TemplateFuncs = template.FuncMap{
+	"dict":               Dict,
 	"AppUrl":             func() string { return "https://gitea.com/" },
 	"AppName":            func() string { return "Gitea" },
-	"DotEscape":          func(s string) template.HTML { return template.HTML(template.HTMLEscapeString(s)) },
+	"AppDomain":          func() string { return "gitea.com" },
+	"DotEscape":          func(s string) string { return strings.ReplaceAll(s, ".", "\u200d.\u200d") },
 	"QueryEscape":        url.QueryEscape,
 	"ShortSha":           ShortSha,
 	"PathEscapeSegments": PathEscapeSegments,
@@ -69,16 +71,7 @@ func FormatByteSize(n int64) string {
 
 // HTMLFormat substitutes %s/%d placeholders with HTML-escaped values.
 func HTMLFormat(fmtStr string, args ...any) template.HTML {
-	result := fmtStr
-	for i, arg := range args {
-		escaped := template.HTMLEscapeString(fmt.Sprint(arg))
-		result = strings.Replace(result, fmt.Sprintf("%%[%d]s", i+1), escaped, 1)
-		if !strings.Contains(result, fmt.Sprintf("%%[%d]s", i+1)) {
-			result = strings.Replace(result, "%s", escaped, 1)
-			result = strings.Replace(result, "%d", fmt.Sprint(arg), 1)
-		}
-	}
-	return template.HTML(result)
+	return template.HTML(fmt.Sprintf(fmtStr, escapedArgs(args)...))
 }
 
 // Dict builds a map from alternating key/value pairs (used by Gitea's Dict function).