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/app/controllers/admin/costs_controller.rb

@@ -0,0 +1,30 @@
+# frozen_string_literal: true
+
+module Admin
+  class CostsController < Admin::BaseController
+    def index
+      @month = parse_month(params[:month]) || Time.zone.today.beginning_of_month
+      analytics = Admin::CostAnalytics.new(month: @month)
+      @summary = analytics.summary
+      @trend = analytics.trend
+      @clubs = analytics.club_breakdown
+      @entries = PlatformCostEntry.for_month(@month).ordered
+      @month_options = month_options(@month)
+    end
+
+    private
+
+    def parse_month(value)
+      return nil if value.blank?
+
+      Date.strptime(value.to_s, "%Y-%m").beginning_of_month
+    rescue ArgumentError, TypeError
+      nil
+    end
+
+    def month_options(selected)
+      start = selected - 23.months
+      (0..23).map { |i| start + i.months }.reverse
+    end
+  end
+end