refactor(frontend) : extract shared components and reduce file sizes

- Extract CustomFieldInputGrid.vue from 6 duplicated template blocks (~70 lines each)
- Extract EntityHistorySection.vue from 3 identical history sections in edit pages
- Extract useDragReorder composable from 4 identical drag-and-drop implementations in StructureNodeEditor (~330 lines → ~30)
- Extract catalogDisplayUtils.ts (resolvePrimaryDocument, resolveSupplierNames, buildSuppliersDisplay)
- Remove redundant computed wrappers (historyEntries, loadingTypes, selectedFiles)
- Remove unused imports (fieldKey, historyActionLabel, formatHistoryDate, *HistoryEntry types)
- Move Intl.DateTimeFormat to module-level in date.ts

Co-Authored-By: Claude Opus 4.6 <noreply@anthropic.com>

app/utils/date.ts

@@ -2,6 +2,12 @@
  * Formatte une date en respectant les conventions françaises (jj/mm/aaaa).
  * Retourne "—" si la valeur est invalide ou absente.
  */
+const frenchDateFormatter = new Intl.DateTimeFormat('fr-FR', {
+  day: '2-digit',
+  month: '2-digit',
+  year: 'numeric',
+})
+
 export const formatFrenchDate = (value: Date | string | number | null | undefined): string => {
   if (value === null || value === undefined || value === '') {
     return '—'
@@ -12,9 +18,5 @@ export const formatFrenchDate = (value: Date | string | number | null | undefine
     return '—'
   }
 
-  return new Intl.DateTimeFormat('fr-FR', {
-    day: '2-digit',
-    month: '2-digit',
-    year: 'numeric',
-  }).format(date)
+  return frenchDateFormatter.format(date)
 }