Allinea card piani: stessa altezza e bordo uniforme.

Flex column con azioni in basso; highlight Premium Light con box-shadow
invece di bordo rosso diverso che spezzava l’allineamento.

Co-authored-by: Cursor <cursoragent@cursor.com>

backend/app/views/shared/_plan_cards.html.erb

@@ -14,7 +14,8 @@
          stripe_subscription_active: stripe_subscription_active?(subscription),
          current_interval: current_interval
        ) : nil %>
-    <div class="plan-card <%= "featured" if plan.slug == current_slug || (!billing_mode && plan.slug == "premium_light") %>">
+    <% featured = billing_mode ? (plan.slug == current_slug) : (plan.slug == "premium_light") %>
+    <div class="plan-card<%= " featured" if featured %>">
       <h3><%= plan.name %></h3>
       <% if plan.slug == "free" %>
         <div class="plan-price">€0</div>