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/mailers/ops/alert_mailer.rb

@@ -0,0 +1,11 @@
+module Ops
+  class AlertMailer < ApplicationMailer
+    def incident(incident)
+      @incident = incident
+      mail(
+        to: ENV.fetch("OPS_ALERT_EMAIL"),
+        subject: "[Match Live TV Ops] #{incident.severity.upcase}: #{incident.title}"
+      )
+    end
+  end
+end