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/routes.rb

@@ -2,6 +2,7 @@ Rails.application.routes.draw do
   mount ActionCable.server => "/cable"
 
   get "up" => "rails/health#show", as: :rails_health_check
+  get "up/deep" => "ops/health#show", as: :ops_deep_health
 
   namespace :api do
     namespace :v1 do
@@ -76,6 +77,13 @@ Rails.application.routes.draw do
 
     root to: "dashboard#index"
     get "metrics", to: "dashboard#metrics"
+    resources :ops, only: [:index], controller: "ops" do
+      member do
+        post :acknowledge
+        post :resolve
+        post :mute
+      end
+    end
     get "billing", to: "billing#index", as: :billing
     post "billing/payments/:payment_id/attach_pdf", to: "billing#attach_pdf", as: :billing_payment_attach_pdf
     resources :teams, only: %i[show]