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/pages/constructeurs.vue

@@ -100,6 +100,7 @@ import { useConstructeurs } from '~/composables/useConstructeurs'
 import { useToast } from '~/composables/useToast'
 import { usePersistedValue } from '~/composables/usePersistedValue'
 import { formatPhone } from '~/utils/formatters/phone'
+import { formatFrenchDate } from '~/utils/date'
 import IconLucidePlus from '~icons/lucide/plus'
 
 const { canEdit } = usePermissions()
@@ -153,16 +154,7 @@ const debouncedSearch = debounce(async () => {
   await searchConstructeurs(searchTerm.value)
 }, 300)
 
-const formatDate = (dateStr) => {
-  if (!dateStr) return '—'
-  const date = new Date(dateStr)
-  if (Number.isNaN(date.getTime())) return '—'
-  return new Intl.DateTimeFormat('fr-FR', {
-    day: '2-digit',
-    month: '2-digit',
-    year: 'numeric',
-  }).format(date)
-}
+const formatDate = formatFrenchDate
 
 const formatPhoneDisplay = (value) => {
   const formatted = formatPhone(value)