Feat: Add inline category creation in catalog with clickable product names

Added inline category creation functionality to catalog page with user-friendly interface:
- Inline input fields for creating root and nested categories
- '+' button in category tree header for root categories
- '+' icon on hover for each category node to create subcategories
- Clickable product/kit names in catalog grid and list views
- AJAX API endpoint for category creation with validation
- User-friendly error messages for duplicate names and constraints
- Clean implementation using clearTimeout pattern to prevent duplicate requests

Technical details:
- New API endpoint: POST /products/api/categories/create/
- Auto-generates slug and SKU for new categories
- Validates uniqueness, parent existence, and circular references
- Single-request submission with proper race condition handling
- Removes debug logging for production-ready code

🤖 Generated with [Claude Code](https://claude.com/claude-code)

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

myproject/products/urls.py

@@ -47,6 +47,7 @@ urlpatterns = [
     path('api/kits/temporary/create/', views.create_temporary_kit_api, name='api-temporary-kit-create'),
     path('api/tags/create/', api_views.create_tag_api, name='api-tag-create'),
     path('api/tags/<int:pk>/toggle/', api_views.toggle_tag_status_api, name='api-tag-toggle'),
+    path('api/categories/create/', api_views.create_category_api, name='api-category-create'),
     path('api/categories/<int:pk>/rename/', api_views.rename_category_api, name='api-category-rename'),
 
     # Photo processing status API (for AJAX polling)