Add admin panel, enhanced search, Gonher import and expand API

- Add admin interface (admin.html, admin.js) for managing catalog data
- Add enhanced search module with advanced filtering capabilities
- Expand server.py with new API endpoints and admin functionality
- Add Gonher catalog import scripts (import_gonher_catalog.py, import_gonher_complete.py)
- Add demo data population script and sample CSV data
- Update customer landing page and dashboard with UI improvements
- Update database with enriched vehicle and parts data

Co-Authored-By: Claude Opus 4.6 <noreply@anthropic.com>

dashboard/sample_data/aftermarket_sample.csv

@@ -0,0 +1,13 @@
+oem_part_id,manufacturer_id,part_number,name,name_es,quality_tier,price_usd,warranty_months
+1,1,P06050,Premium Brake Pad Set,Juego de Pastillas Premium,premium,89.99,36
+1,5,PGD923,Professional Brake Pads,Pastillas Profesionales,standard,49.99,24
+1,14,D923,Economy Brake Pads,Pastillas Economicas,economy,29.99,12
+3,2,72226WS,Premium Oil Filter,Filtro de Aceite Premium,premium,12.99,12
+3,4,PF63E,Professional Oil Filter,Filtro de Aceite Profesional,standard,8.99,12
+4,2,5067WS,Premium Air Filter,Filtro de Aire Premium,premium,24.99,12
+4,3,1A3000,High Flow Air Filter,Filtro de Aire Alto Flujo,premium,29.99,12
+6,9,ILKAR7B11,Iridium IX Spark Plug,Bujia de Iridio IX,premium,14.99,24
+6,2,9652,Platinum Spark Plug,Bujia de Platino,standard,9.99,12
+7,11,T245,Timing Belt,Banda de Tiempo,premium,45.99,36
+8,11,K060685,Serpentine Belt,Banda Serpentina,premium,32.99,24
+8,12,4060685,Multi-V Belt,Banda Multi-V,standard,24.99,12