fix(custom-fields) : fix resolvedStructure declaration order and remove duplicate in usePieceEdit

frontend/app/composables/usePieceEdit.ts

@@ -83,6 +83,12 @@ export function usePieceEdit(pieceId: string) {
   const constructeurIdsFromForm = computed(() => constructeurIdsFromLinks(constructeurLinks.value))
   const productSelections = ref<(string | null)[]>([])
 
+  // Declared early so useCustomFieldInputs can reference it.
+  // selectedType is defined later but is safely accessed inside a computed (lazy evaluation).
+  const resolvedStructure = computed<PieceModelStructure | null>(() =>
+    pieceTypeDetails.value?.structure ?? null,
+  )
+
   const {
     fields: customFieldInputs,
     requiredFilled: requiredCustomFieldsFilled,
@@ -172,10 +178,6 @@ export function usePieceEdit(pieceId: string) {
     return pieceTypeList.value.find((type) => type.id === selectedTypeId.value) ?? null
   })
 
-  const resolvedStructure = computed<PieceModelStructure | null>(() =>
-    pieceTypeDetails.value?.structure ?? selectedType.value?.structure ?? null,
-  )
-
   const structureProducts = computed(() =>
     getStructureProducts(resolvedStructure.value),
   )