Three reusable-widget follow-up fixes:
1. Reference sort_order independently reorderable. Reordering a
referenced widget now updates the widget_references.sort_order (per-
dashboard), not the shared widget instance sort_order. New backend
update_widget_reference method + PUT /api/widgets/references/{id}
endpoint. Frontend moveInstance checks _ref_id to choose the right
mutation (updateRef for references, saveWidget for owned).
2. Detach preserves service_id. detach_widget_reference now copies the
original widget's service_id into the clone, so service-bound widgets
(Grafana chart, Jellyfin activity) continue to render after detach.
3. Named dashboards support widget references. NamedDashboardPage
fetches useWidgetReferences('named:<slug>') and renders them via
WidgetInstanceCard alongside pinned links. 'Edit widgets' button
opens WidgetConfigDialog with dashboardScope='named:<slug>'.
Also: removed useMemo on combinedWidgets in WidgetConfigDialog to fix
a react-hooks/preserve-manual-memoization lint error (the React Compiler
ESLint plugin couldn't verify the spread+sort memoization).
283 backend tests pass (+1 update_reference test); 128 frontend tests
pass; ruff clean; 0 lint errors.
Developer
1e636fdbe2