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/services/payout_service.rb

@@ -8,23 +8,32 @@ class PayoutService
 
     @payout.update!(status: :processing)
 
-    # Create Stripe payout
     begin
-      stripe_payout = Stripe::Payout.create({
-        amount: @payout.amount_cents,
-        currency: 'eur',
-        destination: @payout.user.stripe_account_id,
-        description: "Payout for event: #{@payout.event.name}"
-      })
+      net_amount = @payout.amount_cents - @payout.fee_cents
+      transfer = Stripe::Transfer.create({
+        amount: (net_amount / 100.0).to_i,
+        currency: "eur",
+        destination: @payout.user.stripe_connected_account_id,
+        description: "Payout for event #{@payout.event.name}",
+        metadata: { payout_id: @payout.id, event_id: @payout.event_id }
+      }, idempotency_key: SecureRandom.uuid)
 
       @payout.update!(
         status: :completed,
-        stripe_payout_id: stripe_payout.id
+        stripe_payout_id: transfer.id
       )
+
+      update_earnings_status
     rescue Stripe::StripeError => e
       @payout.update!(status: :failed)
       Rails.logger.error "Stripe payout failed for payout #{@payout.id}: #{e.message}"
       raise e
     end
   end
-end
+
+  private
+
+  def update_earnings_status
+    @payout.event.earnings.where(status: 0).update_all(status: 1)  # pending to paid
+  end
+end