chore: clear the mechanical lint and type findings

Dead imports and locals removed, each blocks keyed, `any` narrowed to unknown.
Two context setters kept their calls and lost only the unused binding; the
settings redirect no longer awaits a parent whose data it discards. A leading
underscore now marks a binding that only holds a position.

frontend/src/lib/components/view/book-thumbnail.svelte

@@ -2,12 +2,11 @@
 	import { resolve } from '$app/paths';
 	import BookImage from './book-image.svelte';
 	import GeneratedCover from './generated-cover.svelte';
-	import { Progress } from '$lib/components/ui/progress/index';
 	import { getLibraryState } from '$lib/state/library.svelte';
 	import { getBookSelectionState } from '$lib/state/bookSelection.svelte';
 	import type { Book } from '$lib/schema';
 
-	let { book, class: className = '', ...rest }: { book: Book; class?: string } = $props();
+	let { book, class: className = '' }: { book: Book; class?: string } = $props();
 
 	const selectionState = getBookSelectionState();
 	const libraryState = getLibraryState();
@@ -78,7 +77,7 @@
 
 	<!-- Authors list -->
 	<p class="line-clamp-1 w-full text-xs text-muted-foreground">
-		{#each book.authors as author}
+		{#each book.authors as author (author.id)}
 			<a
 				href="{resolve('/(root)/(library)/library/[libraryId]/view', {
 					libraryId: String(libraryState.activeLibrary?.id ?? '')