Fix#3638
This is a manual Forgejo-specific version of the Gitea PR https://github.com/go-gitea/gitea/pull/30862. The weekly Forgejo PR #3772 could not cherry-pick this commit due to conflicts (eg subsequent CodeSpell changes).
Only occurs with Webkit in Safari over eg `http://192..`. (not localhost).
See https://webkit.org/blog/10855/async-clipboard-api/
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**Before**
![Before.jpg](/attachments/c570d030-fcce-48ea-ac96-06b624541c7b)
**After**
![After.jpg](/attachments/1a9132ab-f7f3-43a5-b3ea-37b6f2b671c4)
Reviewed-on: https://codeberg.org/forgejo/forgejo/pulls/3805
Reviewed-by: Otto <otto@codeberg.org>
Co-authored-by: David Davies-Payne <d2p@me.com>
Co-committed-by: David Davies-Payne <d2p@me.com>
(cherry picked from commit e4c3c039be)