chore: stop lint rules that do not model runes from reporting

no-unused-expressions is off for Svelte files: a bare `book;` in an $effect
declares a dependency. The URL and Set instances it flagged are local
temporaries, marked individually. The one real finding was visibleApiKeys,
genuine reactive state cloned on every mutation to force an update; it is a
SvelteSet now.

frontend/src/routes/(root)/settings/devices/+page.svelte

@@ -21,11 +21,12 @@
 	import { toast } from 'svelte-sonner';
 	import { invalidateAll } from '$app/navigation';
 	import type { Device } from '$lib/schema/device';
+	import { SvelteSet } from 'svelte/reactivity';
 
 	let { data } = $props();
 
 	let createDialogOpen = $state(false);
-	let visibleApiKeys = $state<Set<string>>(new Set());
+	const visibleApiKeys = new SvelteSet<string>();
 	let deleteConfirmDevice = $state<Device | null>(null);
 	let regenerateConfirmDevice = $state<Device | null>(null);
 
@@ -35,7 +36,6 @@
 		} else {
 			visibleApiKeys.add(deviceId);
 		}
-		visibleApiKeys = new Set(visibleApiKeys);
 	}
 
 	function maskApiKey(apiKey: string): string {