add mobile download page :3

src/libpoketube/init/pages-channel-and-download.js

@@ -47,6 +47,7 @@ module.exports = function (app, config, renderTemplate) {
         color: await modules
           .getColors(`https://i.ytimg.com/vi/${v}/maxresdefault.jpg`)
           .then((colors) => colors[0].hex()),
+           isMobile: req.useragent.isMobile,
       });
     } catch {
       res.redirect("/");