refactor: split models into modules, remove template-based views, and clean up code style

- Split monolithic models.py into models/ package (customers, products, sales, payments, admin)
- Removed forms.py, all HTML templates, and associated template-based views
- Added api/ package with CatalogSaleView placeholder
- Updated all imports across project to use new model paths
- Removed obsolete tests (form, export, purchase, summary tests)
- Removed template-based URL patterns, kept only API endpoints
- Standardized string quotes (single to double) and reformatted code

.env.development

@@ -20,7 +20,7 @@ CORS_ALLOWED_ORIGINS=http://localhost:3000,http://localhost:7001,http://localhos
 # No additional DB configuration needed for SQLite
 
 # Tryton ERP Configuration
-TRYTON_HOST=localhost
-TRYTON_DATABASE=tryton
-TRYTON_USERNAME=admin
-TRYTON_PASSWORD=admin
+TRYTON_HOST=recreo.onecluster.com.co
+TRYTON_DATABASE=ilusion_staging
+TRYTON_USERNAME=alejandro.ayala
+TRYTON_PASSWORD=cl4v3alejo