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/event.rb

@@ -66,24 +66,26 @@ class Event < ApplicationRecord
   # Scope for published events ordered by start time
   scope :upcoming, -> { published.where("start_time >= ?", Time.current).order(start_time: :asc) }
 
+  # Scope for events eligible for payout
+  scope :eligible_for_payout, -> { where("end_time <= ?", Time.current).joins(:earnings).group("events.id").having("SUM(earnings.amount_cents) > 0") }
+
   # === Instance Methods ===
 
   # Payout methods
-  def can_request_payout?
-    event_ended? && earnings.pending.any? && user.can_receive_payouts?
-  end
-
-  def total_earnings_cents
-    # Only count earnings from non-refunded tickets
-    earnings.pending.sum(:amount_cents)
+  def total_gross_cents
+    tickets.active.sum(:price_cents)
   end
 
   def total_fees_cents
-    (total_earnings_cents * 0.1).to_i # 10% platform fee
+    earnings.pending.sum(:fee_cents)
   end
 
   def net_earnings_cents
-    total_earnings_cents - total_fees_cents
+    total_gross_cents - total_fees_cents
+  end
+
+  def can_request_payout?(user = self.user)
+    event_ended? && (net_earnings_cents > 0) && user.is_professionnal? && payouts.pending.empty?
   end
 
   # Check if coordinates were successfully geocoded or are fallback coordinates