Backend:
- Add 'search' param to /brand-parts endpoint (filters oem_part_number and name via ILIKE)
- Keep count query accurate with search filter
Frontend (brand-catalog.js):
- Brand search input: filters 619 brands locally while typing
- Parts pagination: Previous/Next buttons with page counter (50 per page)
- Parts search within category: search input + Enter key triggers backend search
- Visual polish: stock badges, empty-state messages, responsive layout
- Loading states and breadcrumbs improved