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/services/ops/health_checks_spec.rb

@@ -0,0 +1,69 @@
+require "rails_helper"
+
+RSpec.describe Ops::HealthChecks do
+  describe "#call" do
+    it "risolve incidenti quando il disco è sano" do
+      Ops::Incident.create!(
+        kind: "disk_space",
+        severity: "warning",
+        status: "open",
+        title: "Disco",
+        message: "alto",
+        metadata: {},
+        fingerprint: "disk_space:root",
+        occurrence_count: 1,
+        first_seen_at: Time.current,
+        last_seen_at: Time.current
+      )
+
+      allow_any_instance_of(described_class).to receive(:check_disk_root).and_return(
+        described_class::Finding.new(
+          kind: "disk_space", severity: "info", healthy: true,
+          title: "OK", message: "OK", metadata: {}, fingerprint: "disk_space:root"
+        )
+      )
+      %i[
+        check_recordings_size check_postgres check_redis check_mediamtx check_garage
+        check_sidekiq_heartbeat check_sidekiq_dead check_http_public
+      ].each do |method|
+        allow_any_instance_of(described_class).to receive(method).and_return(
+          described_class::Finding.new(
+            kind: "test", severity: "info", healthy: true,
+            title: "OK", message: "OK", metadata: {}, fingerprint: "#{method}:ok"
+          )
+        )
+      end
+
+      described_class.new.call
+
+      expect(Ops::Incident.find_by(fingerprint: "disk_space:root").status).to eq("resolved")
+    end
+  end
+
+  describe "#summary" do
+    it "restituisce status ok quando tutti i check sono sani" do
+      allow_any_instance_of(described_class).to receive(:check_disk_root).and_return(
+        described_class::Finding.new(
+          kind: "disk_space", severity: "info", healthy: true,
+          title: "OK", message: "OK", metadata: {}, fingerprint: "disk_space:root"
+        )
+      )
+      %i[
+        check_recordings_size check_postgres check_redis check_mediamtx check_garage
+        check_sidekiq_heartbeat check_sidekiq_dead check_http_public
+      ].each do |method|
+        allow_any_instance_of(described_class).to receive(method).and_return(
+          described_class::Finding.new(
+            kind: "test", severity: "info", healthy: true,
+            title: "OK", message: "OK", metadata: {}, fingerprint: "#{method}:ok"
+          )
+        )
+      end
+
+      summary = described_class.new.summary
+
+      expect(summary[:status]).to eq("ok")
+      expect(summary[:checks].size).to eq(9)
+    end
+  end
+end