fix(ui): make pagination labels always visible to screenreader

- The pagination labels 'First', 'Previous', 'Next' and 'Last' are
hidden away when the screen width becomes smaller. However this also
hides them from the screen reader. Instead of using `display: none`, use
some well-known tricks to still make them visible to the screen reader.
- Add E2E test.
- Resolves Codeberg/Community#1858

(cherry picked from commit b6072496d4)

tests/e2e/pagination.test.e2e.ts

@@ -0,0 +1,15 @@
+// @watch start
+// template/base/paginate.tmpl
+// services/context/pagination.go
+// @watch end
+
+import {expect} from '@playwright/test';
+import {test} from './utils_e2e.ts';
+import {accessibilityCheck} from './shared/accessibility.ts';
+
+test('Pagination a11y', async ({page}) => {
+  await page.goto('/explore/repos');
+
+  await expect(page.locator('.pagination')).toBeVisible();
+  await accessibilityCheck({page}, ['.pagination'], [], []);
+});