feat: implement 2-step product registration with new catalog fields
Backend:
- Add ean_code, manufacturer, category, subcategory, observations to Product model
- Create migration 0006_product_catalog_fields.sql
- Update repository queries (CreateProduct, ListProducts, ListRecords)
Frontend:
- Create ProductCreate.tsx with 2-step wizard form
- Add route /products/new
- Add 'Cadastrar Produto' button to Inventory page
Seeder:
- Update CREATE TABLE products with new columns
- Update generateProducts with EAN codes and manufacturers
Docs:
- Update database-schema.md with new fields