Forum import: archived comments posted under their original author names

One account per original author (nickname = name as signed on the old
site, group 'Original site'), display-name driver 'museum' keeps the
brackets; --replace re-imports threads without real replies.

Co-Authored-By: Claude Opus 5.5 <noreply@anthropic.com>
Claude-Session: https://claude.ai/code/session_01YDRjtmAiNpo5mK5N3d7QwZ

content/museum/nec-pc-6601.md

@@ -69,7 +69,7 @@ params:
   - adverts
   - links
   - comments
-  forum_thread: 3
+  forum_thread: 9
   photos:
   - title: PC-6601
     subtitle: ''