fix(mappings): resolve 409 error on multi-CODMAT edit and make SKU editable

Batch create after soft-delete was rejected because create_mapping()
treated soft-deleted records as conflicts. Added auto_restore param
that restores+updates instead of 409 when called from edit flow.
Also removed readOnly on SKU input in edit modal.

Co-Authored-By: Claude Opus 4.6 (1M context) <noreply@anthropic.com>

api/app/templates/mappings.html

@@ -154,5 +154,5 @@
 {% endblock %}
 
 {% block scripts %}
-<script src="/static/js/mappings.js?v=5"></script>
+<script src="/static/js/mappings.js?v=7"></script>
 {% endblock %}