add warning on track page if only a snippet is available

lib/sc/track.go

@@ -48,7 +48,9 @@ type Track struct {
 type TrackPolicy string
 
 const (
-	PolicyBlock TrackPolicy = "BLOCK"
+	PolicyBlock TrackPolicy = "BLOCK" // not available (in your country)
+	PolicySnip  TrackPolicy = "SNIP"  // 30-second snippet available
+	PolicyAllow TrackPolicy = "ALLOW" // all good
 )
 
 type Protocol string