feat(file-browser): make entire file card clickable in list view

Improve the user experience in the file browser list view by allowing users to click anywhere on a file card to open it, rather than just the specific link.

- Add a click event listener to the file browser to handle navigation when clicking a card in list view.
- Ensure interactive elements (like buttons or inputs) inside the card do not trigger the card-wide click.
- Add `cursor: pointer` to list view file cards to indicate they are clickable.
- Update retro theme CSS to style the entire card on hover and focus.

backend/static/css/16-retro.css

@@ -708,6 +708,18 @@
   outline-offset: -2px;
 }
 
+:root[data-theme="retro"] .file-browser.is-list .file-card:hover,
+:root[data-theme="retro"] .file-browser.is-list .file-card:focus-within {
+  background: transparent;
+  outline: 2px solid #000078;
+  outline-offset: -2px;
+}
+
+:root[data-theme="retro"] .file-browser.is-list .file-card:hover .file-open,
+:root[data-theme="retro"] .file-browser.is-list .file-card:focus-within .file-open {
+  outline: 0;
+}
+
 :root[data-theme="retro"] .file-media {
   border: 0;
   border-radius: 0;