- When no sub-issues exist, show "Add sub-issue" button alongside
"Upload attachment" and "New document" in the action row
- When sub-issues exist, show them in a dedicated section above
Documents with "Sub-issues" header and "Add sub-issue" button
- Remove the sub-issues tab from the comments/activity tabs
Co-Authored-By: Paperclip <noreply@paperclip.ing>