Rebuild admin pages around DataTable/AdminModal; restructure categories/groups and v2 groups API

Remove the generic $lib/svelte-admin CRUD layer and AdminTable.svelte; each
admin route now owns its own form/modal logic. Add DataTable.svelte,
superform-errors.ts, and profile-specific modal/field components.

Flatten proclamation categories/groups and drop subscription levels; add the
v2 groups API; update v1/v2 endpoints, serializers, auth, and regenerated
Prisma client with the new migrations.

Document the overhaul plan in docs/ADMIN_OVERHAUL.md.

src/lib/components/containers/Window.svelte

@@ -2,6 +2,8 @@
 	let { children } = $props();
 </script>
 
-<div class="flex min-h-0 flex-1 items-center justify-center overflow-auto">
-	{@render children()}
+<div class="mx-auto w-full max-w-md px-4 py-8 sm:py-12">
+	<div class="rounded-2xl border border-slate-200 bg-white p-6 shadow-sm sm:p-8">
+		{@render children()}
+	</div>
 </div>