Admin protetto, dashboard KPI e aggiornamenti sito marketing.

Login admin con cambio password, metriche server (CPU/RAM/disco/banda), grafici e statistiche streaming; sezione piani ridimensionata.

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

backend/app/views/admin/sessions/index.html.erb

@@ -1,11 +1,11 @@
 <h2>Stream Sessions</h2>
-<table>
+  <table class="admin-table">
   <thead><tr><th>Match</th><th>Status</th><th>Disconnects</th><th></th></tr></thead>
   <tbody>
     <% @sessions.each do |s| %>
       <tr>
         <td><%= s.match.team.name %> vs <%= s.match.opponent_name %></td>
-        <td><span class="badge <%= s.live? ? 'live' : 'ended' %>"><%= s.status %></span></td>
+        <td><span class="badge <%= s.status == 'live' ? 'badge--live' : 'badge--paused' %>"><%= s.status %></span></td>
         <td><%= s.disconnection_count %></td>
         <td><%= link_to "Dettaglio", admin_session_path(s) %></td>
       </tr>