HEAVY: finish music service migration, tidy up services, more tests

service/music/music.go

@@ -0,0 +1,18 @@
+package music
+
+import (
+	repository "arimelody-web/repository/music"
+	"log"
+)
+
+type MusicService struct {
+    repo repository.MusicRepository
+    log *log.Logger
+}
+
+func NewMusicService(repo repository.MusicRepository, logger *log.Logger) *MusicService {
+    return &MusicService{
+        repo: repo,
+        log: logger,
+    }
+}