Aggiunge monitoraggio ops: health check, log scanner, dashboard e notifiche.

Introduce incidenti con dedup, job Sidekiq ogni 3 min, scan log cron, /up/deep,
dashboard /admin/ops e push ntfy; include Sentry opzionale e fix test suite.

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

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

@@ -54,6 +54,19 @@
   </div>
 </section>
 
+<section class="panel" style="margin-bottom:1.25rem">
+  <h2>Stato piattaforma (Ops)</h2>
+  <% critical = Ops::Incident.critical_open.count %>
+  <% warnings = Ops::Incident.open.where(severity: "warning").count %>
+  <% if critical.positive? %>
+    <p class="admin-flash" style="margin-bottom:0.75rem"><%= critical %> incidente/i critico/i aperto/i — <%= link_to "Vedi dashboard Ops", admin_ops_path %></p>
+  <% elsif warnings.positive? %>
+    <p class="kpi-sub" style="margin-bottom:0.75rem"><%= warnings %> warning — <%= link_to "Dashboard Ops", admin_ops_path %></p>
+  <% else %>
+    <p class="empty" style="margin:0">Nessun incidente aperto. <%= link_to "Dashboard Ops", admin_ops_path %></p>
+  <% end %>
+</section>
+
 <section class="charts-grid" style="grid-template-columns: repeat(auto-fit, minmax(260px, 1fr));">
   <div class="chart-card">
     <h3>Disco sistema</h3>