Aggiunge abbonamenti omaggio admin per sponsor e promozioni.

Gli admin possono concedere o revocare Premium Light/Full senza Stripe;
il piano omaggio ha priorità sui webhook e la società vede un messaggio dedicato.

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

backend/app/views/admin/clubs/show.html.erb

@@ -0,0 +1,16 @@
+<p style="margin-bottom:16px"><%= link_to "← Tutte le società", admin_clubs_path %></p>
+
+<h2><%= @club.name %></h2>
+<p style="color:#888">
+  Sport: <%= @club.sport %>
+  · <%= link_to "Pagamenti e fatture", admin_billing_path(club_id: @club.id) %>
+</p>
+
+<%= render "admin/clubs/comped_form", club: @club, subscription: @subscription, return_to: admin_club_path(@club) %>
+
+<h3 style="font-size:1rem;margin-top:24px">Squadre</h3>
+<ul>
+  <% @club.teams.order(:name).each do |team| %>
+    <li><%= link_to team.name, admin_team_path(team) %></li>
+  <% end %>
+</ul>