Admin analytics: heatmap per device, anteprima staff e analisi costi.

Separa heatmap mobile/desktop, opt-out analytics per operatori, dashboard costi con KPI e trend mensili.

Co-authored-by: Cursor <cursoragent@cursor.com>

backend/spec/requests/admin/costs_spec.rb

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+# frozen_string_literal: true
+
+require "rails_helper"
+
+RSpec.describe "Admin costs", type: :request do
+  let!(:admin) { AdminAccount.create!(username: "ops-costs", password: "Password123") }
+  let(:month) { Time.zone.today.beginning_of_month }
+
+  before do
+    post admin_login_path, params: { username: admin.username, password: "Password123" }
+    PlatformCostEntry.create!(month: month, label: "Piattaforma", amount_cents: 8_500)
+  end
+
+  it "mostra la dashboard costi" do
+    get admin_costs_path, params: { month: month.strftime("%Y-%m") }
+    expect(response).to have_http_status(:ok)
+    expect(response.body).to include(I18n.t("admin.costs.index.title"))
+    expect(response.body).to include("85.00")
+  end
+
+  it "crea, aggiorna ed elimina una voce di costo" do
+    post admin_cost_entries_path,
+         params: {
+           platform_cost_entry: {
+             month: month.strftime("%Y-%m"),
+             label: "Stream CPX",
+             amount_euros: "42.50",
+             notes: "overflow nodes"
+           }
+         }
+    expect(response).to redirect_to(admin_costs_path(month: month.strftime("%Y-%m")))
+    entry = PlatformCostEntry.find_by(label: "Stream CPX")
+    expect(entry.amount_cents).to eq(4_250)
+
+    patch admin_cost_entry_path(entry),
+          params: { platform_cost_entry: { month: month.strftime("%Y-%m"), label: "Stream CPX", amount_euros: "50" } }
+    expect(response).to redirect_to(admin_costs_path(month: month.strftime("%Y-%m")))
+    expect(entry.reload.amount_cents).to eq(5_000)
+
+    delete admin_cost_entry_path(entry)
+    expect(response).to redirect_to(admin_costs_path(month: month.strftime("%Y-%m")))
+    expect(PlatformCostEntry.find_by(id: entry.id)).to be_nil
+  end
+end