fix: extract sidebar channels into partial template and fix DM channel uid reference

src/snek/templates/web.html

@@ -132,6 +132,7 @@
     app.addEventListener("channel-message", (data) => {
         if (data.channel_uid !== channelUid) {
             if(!isMentionForSomeoneElse(data.message)){
+                channelSidebar.notify(data);
                 app.playSound("messageOtherChannel");
             }