Enforce parameter binding requirement for ConfigurableKitProduct variants

Changes:
1. Removed unused attributesMetadata container from configurablekit_form.html
   - Dead code from old formset-based attribute system
   - 10 lines of unused HTML and templating removed

2. Enhanced formset validation in BaseConfigurableKitOptionFormSet.clean():
   - If product HAS parameters: variants MUST select values for ALL parameters
   - If product HAS NO parameters: variants MUST NOT be created
   - Error message guides user to add parameters first

Business logic:
- ConfigurableKitProduct variants (options) are ALWAYS bound to attribute values
- You cannot create orphan variants without parameter selections
- Each variant must have a value for every product parameter

User experience:
- Clear error message if trying to add variant without parameters
- Enforces proper product structure: parameters first, then variants

🤖 Generated with Claude Code

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

myproject/products/templates/products/configurablekit_form.html

@@ -258,17 +258,6 @@ input[name*="DELETE"] {
                             {% endfor %}
                         </div>
 
-                        <!-- Скрытый контейнер с информацией об атрибутах для JavaScript -->
-                        <div id="attributesMetadata" style="display: none;">
-                            {% for attr in attribute_formset %}
-                                {% if attr.cleaned_data or attr.instance.pk %}
-                                    <div data-attr-name="{{ attr.cleaned_data.name|default:attr.instance.name }}"
-                                         data-attr-id="{{ attr.instance.id }}">
-                                    </div>
-                                {% endif %}
-                            {% endfor %}
-                        </div>
-
                         <button type="button" class="btn btn-sm btn-outline-primary" id="addOptionBtn">
                             <i class="bi bi-plus-circle me-1"></i>Добавить вариант
                         </button>