readding no js theme compatibility?

src/inc/routes/theme.mjs

@@ -0,0 +1,16 @@
+import cfg from "../config.mjs";
+
+export default (router, tpl) => {
+  router.get(/^\/theme\//, async (req, res) => {
+    let theme = req.url.split[1] ?? cfg.websrv.themes[0];
+    if(!cfg.websrv.themes.includes(theme))
+      theme = cfg.websrv.themes[0];
+
+    return res.writeHead(301, {
+      "Cache-Control": "no-cache, public",
+      "Set-Cookie": `theme=${theme}; Path=/`,
+      "Location": req.headers.referer ?? "/"
+    }).end();
+  });
+  return router;
+};