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/composables/useSiteManagement.ts

@@ -3,6 +3,7 @@ import { navigateTo, useRoute } from '#imports'
 import { useSites } from '~/composables/useSites'
 import { useToast } from '~/composables/useToast'
 import { useDocuments } from '~/composables/useDocuments'
+import { useConfirm } from '~/composables/useConfirm'
 import { getFileIcon } from '~/utils/fileIcons'
 import { canPreviewDocument } from '~/utils/documentPreview'
 
@@ -41,6 +42,7 @@ export function useSiteManagement() {
   const { showError, showSuccess } = useToast()
   const { sites, loading, loadSites, createSite, updateSite, deleteSite } = useSites()
   const { uploadDocuments, deleteDocument, loadDocumentsBySite } = useDocuments()
+  const { confirm: confirmDialog } = useConfirm()
 
   const showAddSiteModal = ref(false)
   const showEditSiteModal = ref(false)
@@ -132,7 +134,8 @@ export function useSiteManagement() {
     if (index !== -1) {
       sites.value[index] = {
         ...sites.value[index],
-        ...updated
+        ...updated,
+        id,
       }
     }
   }
@@ -251,9 +254,9 @@ export function useSiteManagement() {
 
   const confirmDeleteSite = async (site: SiteWithDocuments) => {
     if (
-      !confirm(
-        `Êtes-vous sûr de vouloir supprimer le site "${site.name}" ? Cette action est irréversible.`
-      )
+      !await confirmDialog({
+        message: `Êtes-vous sûr de vouloir supprimer le site "${site.name}" ? Cette action est irréversible.`,
+      })
     ) {
       return
     }