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/controllers/ops/health_controller.rb

@@ -0,0 +1,28 @@
+module Ops
+  class HealthController < ActionController::API
+    before_action :authorize_deep_health!
+
+    def show
+      summary = Ops::HealthChecks.new.summary
+      status_code = case summary[:status]
+                    when "ok" then :ok
+                    when "degraded" then :service_unavailable
+                    else :service_unavailable
+                    end
+
+      render json: summary, status: status_code
+    end
+
+    private
+
+    def authorize_deep_health!
+      token = ENV["OPS_HEALTH_TOKEN"].presence
+      return if token.blank?
+
+      provided = request.headers["X-Ops-Token"].presence || params[:token].presence
+      return head :unauthorized if provided.blank?
+
+      head :unauthorized unless ActiveSupport::SecurityUtils.secure_compare(provided, token)
+    end
+  end
+end