feat(pagination): add numbered page-jump buttons to document search

Adds an ellipsis-style numbered page button row (1 … 4 5 6 … 12) to
Pagination.svelte. Buttons are hidden on mobile (sm: breakpoint) and fall
back to the existing prev/next layout. Active page uses brand-navy
background. Client-side clamping via makeHref(entry - 1) satisfies AC3.
i18n key pagination_page_button added for de/en/es.

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

frontend/src/lib/components/Pagination.svelte

@@ -20,6 +20,48 @@ const controlBase =
 	'inline-flex min-h-[44px] min-w-[44px] items-center justify-center gap-1.5 rounded-sm border border-line bg-white px-4 py-2 font-sans text-sm font-bold text-ink';
 const linkBase = `${controlBase} transition-colors hover:bg-surface focus-visible:ring-2 focus-visible:ring-brand-navy focus-visible:ring-offset-2 focus-visible:outline-none`;
 const disabledBase = `${controlBase} cursor-not-allowed opacity-40`;
+const activePageBase =
+	'inline-flex min-h-[44px] min-w-[44px] items-center justify-center rounded-sm border border-brand-navy bg-brand-navy px-4 py-2 font-sans text-sm font-bold text-white';
+
+/**
+ * Builds the sliding window of 1-indexed page numbers to render as buttons.
+ * Always shows: first, last, current, one neighbor each side.
+ * null entries represent ellipsis gaps.
+ */
+const pageWindow = $derived.by(() => {
+	const first = 1;
+	const last = totalPages;
+	const current = page + 1; // convert to 1-indexed
+
+	const windowStart = Math.max(first, current - 1);
+	const windowEnd = Math.min(last, current + 1);
+
+	const result: (number | null)[] = [];
+
+	result.push(first);
+
+	if (windowStart > first + 1) {
+		result.push(null); // left ellipsis
+	} else if (windowStart === first + 1) {
+		result.push(windowStart);
+	}
+
+	for (let p = Math.max(windowStart, first + 1); p <= Math.min(windowEnd, last - 1); p++) {
+		result.push(p);
+	}
+
+	if (windowEnd < last - 1) {
+		result.push(null); // right ellipsis
+	} else if (windowEnd === last - 1) {
+		result.push(windowEnd);
+	}
+
+	if (last > first) {
+		result.push(last);
+	}
+
+	return result;
+});
 </script>
 
 {#if totalPages > 1}
@@ -52,14 +94,54 @@ const disabledBase = `${controlBase} cursor-not-allowed opacity-40`;
 			</span>
 		{/if}
 
+		<!-- Mobile: "Seite X von Y" label (hidden on sm: and above) -->
 		<span
 			data-testid="pagination-page-label"
 			aria-current="page"
-			class="font-sans text-sm text-ink-2"
+			class="font-sans text-sm text-ink-2 sm:hidden"
 		>
 			{m.pagination_page_of({ page: page + 1, total: totalPages })}
 		</span>
 
+		<!-- Desktop: numbered page buttons (hidden below sm:) -->
+		<div data-testid="pagination-pages" class="hidden items-center gap-1 sm:flex">
+			{#each pageWindow as entry, i (i)}
+				{#if entry === null}
+					{#if i === 1}
+						<span
+							data-testid="pagination-ellipsis-left"
+							aria-hidden="true"
+							class="px-2 text-sm text-ink-2">…</span
+						>
+					{:else}
+						<span
+							data-testid="pagination-ellipsis-right"
+							aria-hidden="true"
+							class="px-2 text-sm text-ink-2">…</span
+						>
+					{/if}
+				{:else if entry === page + 1}
+					<span
+						data-testid="pagination-page-{entry}"
+						aria-current="page"
+						aria-label={m.pagination_page_button({ page: entry })}
+						class={activePageBase}
+					>
+						{entry}
+					</span>
+				{:else}
+					<a
+						data-testid="pagination-page-{entry}"
+						aria-label={m.pagination_page_button({ page: entry })}
+						href={makeHref(entry - 1)}
+						class={linkBase}
+					>
+						{entry}
+					</a>
+				{/if}
+			{/each}
+		</div>
+
 		{#if hasNext}
 			<a
 				data-testid="pagination-next"