Weblate: Stored HTML injection in editor search preview

### Impact Weblate's live search preview renders unit `source` and `context` as HTML without escaping. Any contributor whose content reaches those fields stores HTML and CSS that runs inside the authenticated editor of every user who runs a matching search. ### Patches * https://github.com/WeblateOrg/weblate/pull/19422 ### Workarounds Only the search preview on the selected views is affected. ### Resources Weblate thanks @adrgs for reporting this issue responsibly via GitHub.