The batch action toolbar hardcoded status="todo", priority="none", and a
null assignee, so the status/priority/assignee pickers always checked a
fixed row regardless of the selected issues. The batch write itself worked,
but the picker mis-reported the current value, surfacing as "status always
defaults to todo" (MUL-3510). The same defect applied to priority and
assignee, across all five toolbar mount points.
Derive the shared status/priority/assignee of the selected issues via a new
commonIssueFields helper and feed it to the pickers; when the selection is
mixed, pass an empty value so no row is checked. Pickers now accept a
nullable current value, and AssigneePicker gains a `mixed` flag to
distinguish an all-unassigned selection (check "No assignee") from a mixed
one (check nothing). Each call site passes its issue universe, mirroring the
skill list's selected-rows approach.
Adds unit tests for commonIssueFields and a toolbar picker-wiring test.
Co-authored-by: Claude Opus 4.8 <noreply@anthropic.com>
Co-authored-by: multica-agent <github@multica.ai>
