style home page with shell and card list

apply the new design system to the home page: wrap content in a
container/stack shell with a site-header for the logout and today
links, render the texts list as a vertical stack of cards via the
list-cards primitive, and dress the create plan modal with the new
modal/btn classes. js renders each text as an li.card with the
create-plan button preserved so existing cypress hooks (li,
.create-plan, .plan-name, .save-plan, .cancel-plan, ids) keep
matching.

public/js/home.js

@@ -9,9 +9,11 @@ document.addEventListener('DOMContentLoaded', () => {
         const texts = await response.json();
         textsList.innerHTML = texts
             .map(text =>
-                '<li>' + text.name +
-                ' <button class="create-plan" data-text-id="' +
-                text.id + '">Create plan</button></li>'
+                '<li class="card cluster cluster-between">' +
+                '<span class="text-name">' + text.name + '</span>' +
+                '<button class="create-plan btn btn-primary"' +
+                ' data-text-id="' + text.id + '">Create plan</button>' +
+                '</li>'
             )
             .join('');
     }