fix(ui) : phase 1 review fixes — machine context links, type annotations, double arrow

- Add ?from=machine&machineId=xxx query params to entity NuxtLinks in hierarchy
- Add useRoute + machineId computed to ComponentItem, PieceItem, MachineProductsCard
- Add :string type to confirmRemove* handlers in machine page
- Remove unicode arrow from DetailHeader backLabel (icon already provides it)
- Add !isEditMode guard on product links in MachineProductsCard

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

frontend/app/components/DetailHeader.vue

@@ -52,7 +52,7 @@ const backDestination = computed(() => {
 
 const backLabel = computed(() => {
   if (route.query.from === 'machine') {
-    return '← Retour à la machine'
+    return 'Retour à la machine'
   }
   return props.backLinkLabel ?? 'Retour au catalogue'
 })