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>

resources/css/app.css

@@ -243,6 +243,16 @@
     block-size: 100%;
 }
 
+/*
+ * resources/views/livewire/share-download.blade.php: a long file list scrolls on its own, as the
+ * upload page's does, so the download buttons stay near the top of the page. It is the page's main
+ * content, so it may take more of the window.
+ */
+.share-file-list {
+    max-block-size: min(32rem, 60dvh);
+    overflow-y: auto;
+}
+
 /*
  * resources/views/livewire/share-download.blade.php: the private text once the recipient shows it,
  * as it was typed — its line breaks kept and a long word or key wrapped rather than overflowing.