feat(ui): replace native confirm() with DaisyUI modal composable (F7.2)

Create useConfirm composable (promise-based, singleton state) and
ConfirmModal component. Replace all 10 confirm()/window.confirm() calls
across 9 pages and 1 composable.

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

app/pages/product-catalog.vue

@@ -382,10 +382,12 @@ const reload = async () => {
   await loadProducts({ force: true })
 }
 
+const { confirm } = useConfirm()
+
 const confirmDelete = async (product: Record<string, any>) => {
-  const confirmed = window.confirm(
-    `Voulez-vous vraiment supprimer le produit "${product.name}" ?\n\nCette action est irréversible.`,
-  )
+  const confirmed = await confirm({
+    message: `Voulez-vous vraiment supprimer le produit "${product.name}" ?\n\nCette action est irréversible.`,
+  })
   if (!confirmed) {
     return
   }