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/lib/state/bookCollection.svelte.ts

@@ -105,6 +105,7 @@ export class BookCollectionState {
 
 		this.view = next;
 
+		// eslint-disable-next-line svelte/prefer-svelte-reactivity -- local temporary, not reactive state
 		const url = new URL(page.url);
 		url.searchParams.set('view', next);
 		// Not a route to resolve — this is the current URL with one query param
@@ -138,6 +139,7 @@ export class BookCollectionState {
 
 	updateSearchParams() {
 		// Update URL
+		// eslint-disable-next-line svelte/prefer-svelte-reactivity -- local temporary, not reactive state
 		const url = new URL(window.location.href);
 
 		Object.entries(this.filters).forEach(([filter, values]) => {
@@ -215,6 +217,7 @@ export class BookCollectionState {
 		// and skips every page in between.
 		this.currentBookPage = 1;
 
+		// eslint-disable-next-line svelte/prefer-svelte-reactivity -- local temporary, not reactive state
 		const urlParams = new URLSearchParams(window.location.search);
 
 		// Re-read sort and filter state from URL