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/spec/rails_helper.rb

@@ -3,6 +3,8 @@ require_relative "../config/environment"
 require "rspec/rails"
 
 RSpec.configure do |config|
+  config.include ActiveSupport::Testing::TimeHelpers
+
   config.use_transactional_fixtures = true
   config.infer_spec_type_from_file_location!
   config.filter_rails_from_backtrace!