server: better structure album tracks endpoint

- client: add now-playing and recommendations to home right-sidebar

src/components/RightSideBar/Recommendation.vue

@@ -18,6 +18,10 @@
 export default {
   setup() {
     const songs = [
+      {
+        title: "Imagine",
+        artist: "John Lennon",
+      },
       {
         title: "Mockingbird",
         artist: "Eminem",
@@ -73,4 +77,4 @@ export default {
 .r-tracks .tracks .song-item .title {
   margin: 0;
 }
-</style>
+</style>