Upgrade heatmaps stile Hotjar: movimenti mouse e anteprima pagina live.

Traccia i movimenti aggregati, overlay a gradienti sull’iframe della pagina e toggle click/move in admin.

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

backend/app/models/analytics_page_cell.rb

@@ -9,4 +9,5 @@ class AnalyticsPageCell < ApplicationRecord
   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 }
+  validates :move_count, numericality: { greater_than_or_equal_to: 0 }
 end