API: Sort tags before saving

Tags should be alphabetically sorted before saving. Whilst this was the behavior with automated tagging, it did not apply to manually set tags via the API.

storage/tags.go

@@ -22,6 +22,8 @@ func SetTags(id string, tags []string) error {
 		}
 	}
 
+	sort.Strings(applyTags)
+
 	tagJSON, err := json.Marshal(applyTags)
 	if err != nil {
 		logger.Log().Errorf("[db] setting tags for message %s", id)