Fix issue sorting and timestamps

Issues should be sorted by creation time and we should show the creation
time as the issue timestamp. Otherwise edits will reorder the comment
thread.

src/components/Thread.svelte

@@ -115,7 +115,7 @@
               author={reply.author}
               caption="replied"
               reactions={reply.reactions}
-              timestamp={reply.edits.slice(-1)[0].timestamp}
+              timestamp={reply.edits[0].timestamp}
               body={reply.edits.slice(-1)[0].body}
               editComment={editComment &&
                 canEditComment(reply.author.did) &&

src/views/repo/Issue.svelte

@@ -69,10 +69,7 @@
         root: thread,
         replies: issue.discussion
           .filter(comment => comment.replyTo === thread.id)
-          .sort(
-            (a, b) =>
-              a.edits.slice(-1)[0].timestamp - b.edits.slice(-1)[0].timestamp,
-          ),
+          .sort((a, b) => a.edits[0].timestamp - b.edits[0].timestamp),
       };
     }, []);