[Enhancement] Allow posts to be marked as duplicates across communities.

[RokeJulianLockhart]

Rationale

Duplicate posts cannot be marked as such across communities. This causes duplication of effort: ¹

Duplicate, but currently we can't close a question in one category as a dupe of an article in another. Working on that, but in the meantime I'll leave a placeholder answer to point the way.

Desired Solution

Allow posts to be marked as duplicates across communities.

Alternatives Considered

meta.codidact.com/posts/294823 describes a theoretical alternative. ²

Additional Context

This depends upon issues/1372, to be useful.

I do not believe that this duplicates issues/698.

forum.codidact.org/t/1051 may also discuss this, but I am unable to access it, due to what issues/11#issue-4484947972 describes.

Footnotes

1. meta.codidact.com/comments/thread/9224#comment-23408 ↩

2. ./296172#answer-296172 ↩

[cellio]

Part of the issue in that particular case is that we can't currently mark questions as duplicates of non-questions, in that case an article. (That doesn't invalidate this request; I'm just pointing out that there's another factor in that case but not all cases.)