feat: add playlist_id to serialized basic program entry

program/models.py

@@ -699,3 +699,9 @@ class ProgramEntry:
     end: datetime.datetime
     show: Show
     timeslot: TimeSlot | None
+
+    def playlist_id(self) -> int | None:
+        if self.timeslot and self.timeslot.playlist_id:
+            return self.timeslot.playlist_id
+        else:
+            return self.show.default_playlist_id

program/serializers.py

@@ -1293,6 +1293,7 @@ class BasicProgramEntrySerializer(serializers.Serializer):
     start = serializers.DateTimeField()
     end = serializers.DateTimeField()
     timeslot_id = serializers.IntegerField(allow_null=True, source="timeslot.id")
+    playlist_id = serializers.IntegerField(allow_null=True)
     show_id = serializers.IntegerField(source="show.id")