refactor(admin): replace window.confirm with ConfirmService in admin user delete

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

frontend/src/routes/admin/users/[id]/+page.svelte

@@ -2,17 +2,29 @@
 import { enhance } from '$app/forms';
 import { beforeNavigate, goto } from '$app/navigation';
 import { m } from '$lib/paraglide/messages.js';
+import { getConfirmService } from '$lib/services/confirm.svelte.js';
 import UserProfileSection from '$lib/components/user/UserProfileSection.svelte';
 import UserGroupsSection from '$lib/components/user/UserGroupsSection.svelte';
 import UserPasswordSection from '$lib/components/user/UserPasswordSection.svelte';
 
 let { data, form } = $props();
 
+const { confirm } = getConfirmService();
+
 const selectedGroupIds = $derived(data.editUser.groups?.map((g: { id: string }) => g.id) ?? []);
 
 let isDirty = $state(false);
 let showUnsavedWarning = $state(false);
 let discardTarget: string | null = $state(null);
+let deleteFormEl = $state<HTMLFormElement | null>(null);
+
+async function handleDelete() {
+	const confirmed = await confirm({
+		title: m.admin_user_delete_confirm({ username: data.editUser.username }),
+		destructive: true
+	});
+	if (confirmed) deleteFormEl!.requestSubmit();
+}
 
 beforeNavigate(({ cancel, to }) => {
 	if (isDirty) {
@@ -51,20 +63,10 @@ $effect(() => {
 		<h2 class="flex-1 font-sans text-sm font-bold text-ink">
 			{m.admin_user_edit_heading({ username: data.editUser.username })}
 		</h2>
-		<form
-			method="POST"
-			action="?/delete"
-			use:enhance={({ cancel }) => {
-				if (!confirm(m.admin_user_delete_confirm({ username: data.editUser.username }))) {
-					cancel();
-				}
-				return async ({ update }) => {
-					await update();
-				};
-			}}
-		>
+		<form bind:this={deleteFormEl} method="POST" action="?/delete" use:enhance>
 			<button
-				type="submit"
+				type="button"
+				onclick={handleDelete}
 				class="rounded-sm border border-red-200 bg-red-50 px-3 py-1 font-sans text-xs font-bold tracking-widest text-red-700 uppercase transition-colors hover:bg-red-100 dark:border-red-900 dark:bg-red-950/30 dark:text-red-400"
 			>
 				{m.btn_delete()}…