feat(library): simplify search/filter UX with expandable search and filter popover

Commit notes

- Replace LibraryFilters component with LibrarySearchFilter in header - Add button group with search icon that expands to input field on click - Add filter button that opens popover with all filter options - Implement micro animation for search expansion (200ms ease-out) - Move search/filter controls inline with Library title and SSE badge - Group all filters (Tags, Mood, BPM, Key, Sort) in collapsible sections - Add filter count badge when filters are active - Preserve selection indicator functionality

Co-authored-by: armin.naimi <[email redacted]>