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/config/initializers/ops_log_subscriber.rb

@@ -0,0 +1,21 @@
+if Rails.env.production? && ENV["OPS_LOG_SUBSCRIBER"] == "true"
+  ActiveSupport::Notifications.subscribe("process_action.action_controller") do |*args|
+    event = ActiveSupport::Notifications::Event.new(*args)
+    next unless event.payload[:status].to_i >= 500
+
+    Ops::IncidentRecorder.record(
+      kind: "log_pattern",
+      severity: "warning",
+      title: "HTTP 500 in Rails",
+      message: "#{event.payload[:method]} #{event.payload[:path]} → #{event.payload[:status]}",
+      metadata: {
+        "controller" => event.payload[:controller],
+        "action" => event.payload[:action],
+        "status" => event.payload[:status]
+      },
+      fingerprint: "rails_500:#{event.payload[:controller]}##{event.payload[:action]}"
+    )
+  rescue StandardError => e
+    Rails.logger.warn("[Ops::LogSubscriber] #{e.message}")
+  end
+end