As an event participant, I want to claim or be assigned an article on the worklist, so that two people don't unknowingly work on the same article and duplicate effort.
Context: A recurring pain point across communities. Note the distinction between claiming an article to create versus claiming a task on an existing article, which affects scope.
Acceptance criteria:
- A participant can mark an article as claimed, and this is visible to others.
- The claimed state shows who claimed it.
- A claim can be released or reassigned.
- Decision recorded on whether claiming is per-article or per-task.
