Carry the source transcript into forks and cross-link fork points

mac/Sources/Byre/Store.swift

@@ -164,8 +164,8 @@ final class Store {
         }
     }
 
-    var transcript: [ByreEvent] {
-        selectedFeed?.events ?? []
+    var transcript: ArraySlice<ByreEvent> {
+        selectedFeed?.own ?? []
     }
 
     var selectedFeed: Feed? {
@@ -439,7 +439,7 @@ final class Store {
                 break
             }
         }
-        feed.load(got)
+        feed.load(got, inherited: got.prefix { $0.taskId != taskId }.count)
     }
 
     private func taskFeed(_ taskId: String) -> Feed {