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

tools/tools.go

@@ -15,6 +15,8 @@ func main() {
 		Usage:     "Gitea Mail Templates CLI — manage and preview email template themes",
 		UsageText: "tools <command> [args...] [--flags]",
 		Commands: []*cli.Command{
+			cmds.UpstreamCommand(),
+			cmds.BuildCommand(),
 			cmds.ListCommand(),
 			cmds.CreateCommand(),
 			cmds.DeleteCommand(),