feat(versioning) : add entity versioning frontend with restore flow

- useEntityVersions composable (list, preview, restore API calls)
- EntityVersionList component with auto-refresh after save
- VersionRestoreModal with context-aware messages per entity type
- Integrate into machine, composant, piece, product detail pages
- Add restore action label to historyDisplayUtils
- Show structure slots in composant/piece consultation mode

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

app/pages/product/[id]/edit.vue

@@ -189,6 +189,14 @@
           :field-labels="historyFieldLabels"
         />
 
+        <EntityVersionList
+          entity-type="product"
+          :entity-id="String(route.params.id)"
+          :field-labels="historyFieldLabels"
+          :refresh-key="versionRefreshKey"
+          @restored="loadProduct()"
+        />
+
         <div class="flex flex-col gap-3 md:flex-row md:justify-end">
           <NuxtLink to="/product-catalog" class="btn btn-ghost" :class="{ 'btn-disabled': saving }">
             Annuler
@@ -243,6 +251,7 @@ import {
 } from '~/shared/utils/customFieldFormUtils'
 
 const { canEdit } = usePermissions()
+const versionRefreshKey = ref(0)
 const route = useRoute()
 const router = useRouter()
 const toast = useToast()
@@ -510,6 +519,7 @@ const submitEdition = async () => {
         return
       }
       toast.showSuccess('Produit mis à jour avec succès')
+      versionRefreshKey.value++
     }
   } catch (error: any) {
     toast.showError(humanizeError(error?.message) || 'Impossible de mettre à jour le produit')