fix : code review — correct 15 issues across UX overhaul (phases 1-4)

Critical fixes:
- Make MigrateConstructeurLinks migration no-op (legacy tables already dropped)
- Add explicit ON CONFLICT (id) target in RestoreConstructeurLinks migration
- Replace N+1 queries with 4 bulk GROUP BY in ConstructeurStatsController
- Declare missing versionListRef template ref in machine detail page
- Add missing await on removeMachineDocument, cast activeTab as string

Important fixes:
- Add lang="ts" to ToastContainer and constructeurs page
- Type entityType as union in UsedInSection/useUsedIn
- Remove dead duration param from showError
- Update back-link props to new /catalogues/* URLs (3 pages)
- Replace raw error blocks with EmptyState in component/piece detail pages
- Type handleFillEntity params and machineInfoCardRef

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

frontend/app/pages/product/[id]/index.vue

@@ -39,7 +39,7 @@
             :subtitle="isEditMode ? 'Ajustez les informations du produit et ses champs personnalisés.' : undefined"
             :is-edit-mode="isEditMode"
             :can-edit="canEdit"
-            back-link="/product-catalog"
+            back-link="/catalogues/produits"
             @toggle-edit="isEditMode = !isEditMode"
           />