feat(documents): paginate search with a Pagination control

Frontend side of the /documents pagination work. The page.server.ts load
reads ?page= from the URL, forwards page+size=50 to the backend, and
exposes the new totalElements/pageNumber/pageSize/totalPages fields on
`data`. +page.svelte renders a <Pagination> component below the result
list; buildPageHref preserves every filter param and only updates page.
The existing triggerSearch debounce flow intentionally drops `page`
when any filter changes, so filter edits reset to page 0 automatically.

<Pagination> uses plain <a href> links (not goto) so SvelteKit's default
scroll restoration scrolls new pages to the top — the expected senior-UX
behaviour. Decorative chevrons wrapped in aria-hidden spans, 44px touch
targets, focus-visible ring, stacks vertically under 640px. The control
hides itself when totalPages ≤ 1.

Test coverage: 9 cases on Pagination (label, aria-current, prev/next
enable/disable, makeHref invocation, decorative chevron, touch target),
plus a filter-reset assertion on +page.svelte (page 5 → edit q →
goto URL must drop page=). Adds i18n keys in de/en/es. Manual edit to
api.ts pending a post-merge npm run generate:api against a rebuilt
dev backend. (#315)

Co-Authored-By: Claude Opus 4.7 <noreply@anthropic.com>

frontend/src/lib/components/Pagination.svelte

@@ -0,0 +1,58 @@
+<script lang="ts">
+import * as m from '$lib/paraglide/messages.js';
+
+interface Props {
+	/** 0-indexed current page. */
+	page: number;
+	/** Total number of pages. `0` or `1` hides the control as trivially there's nothing to navigate. */
+	totalPages: number;
+	/** Given a 0-indexed page number, returns the href the link should point at. */
+	makeHref: (page: number) => string;
+	/** Optional override for the outer `<nav>`'s aria-label. */
+	ariaLabel?: string;
+}
+
+const { page, totalPages, makeHref, ariaLabel }: Props = $props();
+
+const hasPrev = $derived(page > 0);
+const hasNext = $derived(page < totalPages - 1);
+const linkBase =
+	'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 transition-colors hover:bg-surface focus-visible:ring-2 focus-visible:ring-brand-navy focus-visible:ring-offset-2 focus-visible:outline-none aria-disabled:pointer-events-none aria-disabled:cursor-not-allowed aria-disabled:opacity-40';
+</script>
+
+{#if totalPages > 1}
+	<nav
+		aria-label={ariaLabel ?? m.pagination_nav_label()}
+		class="mt-6 flex flex-col items-center gap-3 sm:flex-row sm:justify-between"
+	>
+		<a
+			data-testid="pagination-prev"
+			aria-label={m.pagination_prev()}
+			aria-disabled={!hasPrev}
+			href={hasPrev ? makeHref(page - 1) : undefined}
+			class={linkBase}
+		>
+			<span aria-hidden="true">«</span>
+			{m.pagination_prev()}
+		</a>
+
+		<span
+			data-testid="pagination-page-label"
+			aria-current="page"
+			class="font-sans text-sm text-ink-2"
+		>
+			{m.pagination_page_of({ page: page + 1, total: totalPages })}
+		</span>
+
+		<a
+			data-testid="pagination-next"
+			aria-label={m.pagination_next()}
+			aria-disabled={!hasNext}
+			href={hasNext ? makeHref(page + 1) : undefined}
+			class={linkBase}
+		>
+			{m.pagination_next()}
+			<span aria-hidden="true">»</span>
+		</a>
+	</nav>
+{/if}

frontend/src/lib/components/Pagination.svelte.spec.ts

@@ -0,0 +1,84 @@
+import { describe, it, expect, afterEach, vi } from 'vitest';
+import { cleanup, render } from 'vitest-browser-svelte';
+import { page } from 'vitest/browser';
+
+import Pagination from './Pagination.svelte';
+
+afterEach(() => {
+	cleanup();
+});
+
+const makeHref = (p: number) => `/documents?page=${p}`;
+
+describe('Pagination', () => {
+	it('renders the page-of-total label for the current page', async () => {
+		render(Pagination, { page: 2, totalPages: 10, makeHref });
+
+		const label = page.getByTestId('pagination-page-label');
+		await expect.element(label).toHaveTextContent(/3/); // page is 0-indexed, label is 1-indexed
+		await expect.element(label).toHaveTextContent(/10/);
+	});
+
+	it('marks the current page label with aria-current="page"', async () => {
+		render(Pagination, { page: 0, totalPages: 3, makeHref });
+
+		const label = page.getByTestId('pagination-page-label');
+		await expect.element(label).toHaveAttribute('aria-current', 'page');
+	});
+
+	it('renders prev as a link pointing at page - 1 when not on first page', async () => {
+		render(Pagination, { page: 4, totalPages: 10, makeHref });
+
+		const prev = page.getByTestId('pagination-prev');
+		await expect.element(prev).toHaveAttribute('href', '/documents?page=3');
+	});
+
+	it('disables prev on page 0 (no href, aria-disabled="true")', async () => {
+		render(Pagination, { page: 0, totalPages: 3, makeHref });
+
+		const prev = page.getByTestId('pagination-prev');
+		await expect.element(prev).toHaveAttribute('aria-disabled', 'true');
+		await expect.element(prev).not.toHaveAttribute('href');
+	});
+
+	it('renders next as a link pointing at page + 1 when not on last page', async () => {
+		render(Pagination, { page: 0, totalPages: 3, makeHref });
+
+		const next = page.getByTestId('pagination-next');
+		await expect.element(next).toHaveAttribute('href', '/documents?page=1');
+	});
+
+	it('disables next on the last page (no href, aria-disabled="true")', async () => {
+		render(Pagination, { page: 2, totalPages: 3, makeHref });
+
+		const next = page.getByTestId('pagination-next');
+		await expect.element(next).toHaveAttribute('aria-disabled', 'true');
+		await expect.element(next).not.toHaveAttribute('href');
+	});
+
+	it('calls makeHref with p-1 and p+1', async () => {
+		const spy = vi.fn(makeHref);
+		render(Pagination, { page: 3, totalPages: 10, makeHref: spy });
+
+		const calls = spy.mock.calls.map((c) => c[0]).sort((a, b) => a - b);
+		expect(calls).toContain(2);
+		expect(calls).toContain(4);
+	});
+
+	it('renders decorative chevron inside aria-hidden span so screen readers skip it', async () => {
+		render(Pagination, { page: 1, totalPages: 3, makeHref });
+
+		const prev = page.getByTestId('pagination-prev');
+		await expect
+			.element(prev.getByText('«', { exact: true }))
+			.toHaveAttribute('aria-hidden', 'true');
+	});
+
+	it('prev and next have min 44px touch targets', async () => {
+		render(Pagination, { page: 1, totalPages: 3, makeHref });
+
+		const prev = page.getByTestId('pagination-prev');
+		await expect.element(prev).toHaveClass(/min-h-\[44px\]/);
+		await expect.element(prev).toHaveClass(/min-w-\[44px\]/);
+	});
+});