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/layouts/admin.html.erb

@@ -16,6 +16,10 @@
     <nav class="admin-nav">
       <% if admin_logged_in? %>
         <%= link_to "Dashboard", admin_root_path, class: ("active" if controller_name == "dashboard") %>
+        <% ops_critical = Ops::Incident.critical_open.count %>
+        <%= link_to admin_ops_path, class: ("active" if controller_name == "ops") do %>
+          Ops<% if ops_critical.positive? %> <span class="admin-nav-badge"><%= ops_critical %></span><% end %>
+        <% end %>
         <%= link_to "Società e squadre", admin_clubs_path, class: ("active" if controller_name.in?(%w[clubs teams])) %>
         <%= link_to "Fatturazione", admin_billing_path, class: ("active" if controller_name.in?(%w[billing billing_invoices])) %>
         <%= link_to "YouTube", admin_youtube_platform_path, class: ("active" if controller_name == "youtube") %>