Aggiunge heatmaps first-party (click/scroll) con pagina admin Analytics.

Raccoglie eventi aggregati dietro consenso cookie, senza PII né tracking su admin/regia/live/replay; GA4 resta invariato.

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

backend/app/models/analytics_page_cell.rb

@@ -0,0 +1,12 @@
+# frozen_string_literal: true
+
+class AnalyticsPageCell < ApplicationRecord
+  self.table_name = "analytics_page_cells"
+
+  GRID_SIZE = 40
+
+  validates :day, :page_path, :device, :cell_x, :cell_y, presence: true
+  validates :device, inclusion: { in: AnalyticsEvent::DEVICES }
+  validates :cell_x, :cell_y, inclusion: { in: 0...(GRID_SIZE) }
+  validates :click_count, numericality: { greater_than_or_equal_to: 0 }
+end