fix(ui): replace native confirm() dialogs with the global in-app modal

window.confirm blocks the JS event loop, which froze companion remote
input while open — the remote user could raise the mesh "Clear" prompt
(or reboot / backup-delete / uninstall confirms) and then never dismiss
it, because the synthetic events that would dismiss it queue behind the
dialog itself.

New promise-based appConfirm() (useAppConfirm.ts) + one AppConfirmModal
mounted globally in App.vue, built on BaseModal (Teleport-to-body,
full-viewport backdrop, glass card — the canonical modal contract). All
six native confirm() call sites migrated: mesh clear-all, mesh message
delete, dashboard reboot, backup delete, backup USB copy, app uninstall.

Co-Authored-By: Claude Fable 5 <noreply@anthropic.com>

neode-ui/src/views/ContainerAppDetails.vue

@@ -125,6 +125,7 @@ import { ref, computed, onMounted, onUnmounted } from 'vue'
 import { useRoute, useRouter } from 'vue-router'
 import { useI18n } from 'vue-i18n'
 import { useContainerStore } from '@/stores/container'
+import { appConfirm } from '@/composables/useAppConfirm'
 import { type ContainerStatus as ContainerStatusData } from '@/api/container-client'
 import ContainerStatus from '@/components/ContainerStatus.vue'
 import BackButton from '@/components/BackButton.vue'
@@ -325,7 +326,12 @@ onUnmounted(() => {
 })
 
 async function handleRemove() {
-  if (!confirm(t('apps.uninstallConfirm', { name: appName.value }))) {
+  const ok = await appConfirm({
+    message: t('apps.uninstallConfirm', { name: appName.value }),
+    confirmLabel: t('apps.uninstallTitle'),
+    danger: true,
+  })
+  if (!ok) {
     return
   }