Redesign emex_* tables from vehicle-centric to catalog-centric structure with
junction tables (emex_vehicle_group_links, emex_vehicle_part_links). Migrate
92M+ rows from emex DB via postgres_fdw. Add EmexCatalogService for browse
and VIN pre-scraped matching, with Redis caching. Frontend catalog page now
has PL24/Emex tabs with full drill-down routes (brand → vehicle → group → parts).
Co-Authored-By: Claude Opus 4.6 <noreply@anthropic.com>
