fix: Extract data property in all template refresh calls

After adding/deleting parameters or parts, template refresh was not
extracting the data property from API response, causing editingTemplate.id
to become undefined and Parameters/Parts sections to disappear.

Fixed in:
- addParameter (after adding parameter)
- deleteParameter (after deleting parameter)
- addPart (after adding part)
- deletePart (after deleting part)
- saveConstraints (after updating part constraints)

Author: jackn

frontend/src/pages/Configurator.tsx

@@ -255,7 +255,8 @@ function Configurator() {
 
       // Refresh template
       const refreshed = await fetch(`/api/v1/configurator/templates/${editingTemplate.id}`);
-      const data = await refreshed.json();
+      const response_data = await refreshed.json();
+      const data = response_data.data || response_data;
       setEditingTemplate(data);
 
       // Reset form
@@ -281,7 +282,8 @@ function Configurator() {
       // Refresh template
       if (editingTemplate) {
         const refreshed = await fetch(`/api/v1/configurator/templates/${editingTemplate.id}`);
-        const data = await refreshed.json();
+        const response_data = await refreshed.json();
+        const data = response_data.data || response_data;
         setEditingTemplate(data);
       }
 
@@ -314,7 +316,8 @@ function Configurator() {
 
       // Refresh template
       const refreshed = await fetch(`/api/v1/configurator/templates/${editingTemplate.id}`);
-      const data = await refreshed.json();
+      const response_data = await refreshed.json();
+      const data = response_data.data || response_data;
       setEditingTemplate(data);
 
       setPartSearchOpen(false);
@@ -338,7 +341,8 @@ function Configurator() {
       // Refresh template
       if (editingTemplate) {
         const refreshed = await fetch(`/api/v1/configurator/templates/${editingTemplate.id}`);
-        const data = await refreshed.json();
+        const response_data = await refreshed.json();
+        const data = response_data.data || response_data;
         setEditingTemplate(data);
       }
 
@@ -366,7 +370,8 @@ function Configurator() {
       // Refresh template
       if (editingTemplate) {
         const refreshed = await fetch(`/api/v1/configurator/templates/${editingTemplate.id}`);
-        const data = await refreshed.json();
+        const response_data = await refreshed.json();
+        const data = response_data.data || response_data;
         setEditingTemplate(data);
       }