feat: standardise query parameter name

gmus-backend/README.md

@@ -80,6 +80,6 @@ Fetches next song info.
 
 Fetches previous song info.
 
-#### `GET /shuffle-song?current-song-id=<id>`
+#### `GET /shuffle-song?id=<id>`
 
-Fetches shuffled song info. Note that `current-song-id` is an optional query parameter.
+Fetches shuffled song info. Note that `id` is an optional query parameter specifying the currently playing song.

gmus-backend/pkg/server/fetch.go

@@ -266,7 +266,7 @@ func routeFetchPrevSong(l *logger.Logger, rdb redis.Cmdable, w http.ResponseWrit
 }
 
 func routeFetchShuffledSong(l *logger.Logger, rdb redis.Cmdable, w http.ResponseWriter, r *http.Request) error {
-	idRaw := r.URL.Query().Get("current-song-id")
+	idRaw := r.URL.Query().Get("id")
 	id, err := strconv.Atoi(idRaw)
 	db := database.GetConnection()