cover: tweak styles:

- `optimizeQuality` > `smooth` (CSS language evolution)
- Use `auto` instead of a fixed width.
- Add exceptions for heights and apply them to some previously modified templates.
- Remove `is-large` exception.
- Widen the content column on list curation.

bookwyrm/templates/import_status.html

@@ -125,7 +125,7 @@
             <td>
                 {% if item.book %}
                 <a href="/book/{{ item.book.id }}">
-                {% include 'snippets/book_cover.html' with book=item.book cover_class='is-small' %}
+                {% include 'snippets/book_cover.html' with book=item.book cover_class='is-h-small' %}
                 </a>
                 {% endif %}
             </td>