* feat(dashboard): add search/filter input to the dashboard sidebar (#4013)
Adds a search box at the top of the expanded sidebar that filters nav
sections/groups/items client-side by label, so users don't have to
hunt through the growing nav tree. Reuses the existing common.search /
common.noResults i18n keys (no new locale edits needed) and the shared
Input icon="search" pattern. Matching sections auto-expand while
searching and the accordion/pin state is restored once the query is
cleared.
Filtering logic is extracted into a pure filterSidebarSectionsByQuery()
helper (src/shared/utils/sidebarSearch.ts) so it is trivially unit
testable independent of React/next-intl/next-navigation.
* fix(test): move Sidebar.search test to a runner-collected path (test-discovery gate)
