feat(payouts): implement promoter earnings viewing, request flow, and admin Stripe processing with webhooks

Add model methods for accurate net calculations (€0.50 + 1.5% fees), eligibility, refund handling
Update promoter/payouts controller for index (pending events), create (eligibility checks)
Integrate admin processing via Stripe::Transfer, webhook for status sync
Enhance views: index pending cards, events/show preview/form
Add comprehensive tests (models, controllers, service, integration); run migrations

app/models/user.rb

@@ -65,6 +65,19 @@ class User < ApplicationRecord
   end
 
   def can_receive_payouts?
-    has_stripe_account? && promoter?
+    stripe_connected_account_id.present? && stripe_connect_verified?
+  end
+  private
+
+  def stripe_connect_verified?
+    return false unless stripe_connected_account_id.present?
+
+    begin
+      account = Stripe::Account.retrieve(stripe_connected_account_id)
+      account.charges_enabled
+    rescue Stripe::StripeError => e
+      Rails.logger.error "Failed to verify Stripe account #{stripe_connected_account_id}: #{e.message}"
+      false
+    end
   end
 end