feat(graphql): add buffer to calendar entries

Author: sifferhans

bccm_core/lib/src/features/graphql/queries/live/calendar_days.graphql

@@ -7,25 +7,28 @@ query GetCalendarDay($date: Date!) {
 }
 
 fragment CalendarEntry on CalendarEntry {
+  __typename
   id
   title
   description
   start
   end
-  __typename
+  buffer {
+    url
+    availableUntil
+  }
   ... on EpisodeCalendarEntry {
+    id
     episode {
+      __typename
       id
       publishDate
       image(style: default)
       locked
-      __typename
     }
-    id
   }
   ... on SimpleCalendarEntry {
     id
-    __typename
   }
 }