Scroll a long file list on the download page on its own

A share with hundreds of files made the download page as tall as its
list, so the recipient scrolled far past the buttons. The list now sits
in .share-file-list, capped at min(32rem, 60dvh) with its own scroll, as
the upload page's selected-files list already is; the download buttons
stay on the first screen.

Co-Authored-By: Claude Opus 5.5 <noreply@anthropic.com>

tests/Browser/ShareFlowTest.php

@@ -297,3 +297,19 @@ test('Browse Folder picks a whole folder and keeps each file\'s path in it', fun
     $page->assertSee('holiday/docs/notes.txt')
         ->assertNoJavaScriptErrors();
 });
+
+test('a long file list scrolls on its own and keeps the download buttons on the first screen', function () {
+    $share = app(ShareService::class)->createShare(collect(range(1, 40))->map(fn (int $number): array => [
+        'file' => UploadedFile::fake()->createWithContent("file-{$number}.txt", "file {$number}"),
+        'relativePath' => null,
+    ])->all());
+
+    $page = ready(visit(route('share.download', $share, false))->resize(1280, 800));
+
+    $page->assertScript("(() => {
+        const list = document.querySelector('[data-test=share-file-list]');
+        return list.scrollHeight > list.clientHeight && getComputedStyle(list).overflowY === 'auto';
+    })()")
+        ->assertScript("[...document.querySelectorAll('[data-md-button]')].filter((button) => button.offsetParent !== null && button.textContent.trim().toLowerCase().startsWith('download all')).every((button) => button.getBoundingClientRect().bottom <= window.innerHeight)")
+        ->assertNoJavaScriptErrors();
+});