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/order.rb

@@ -3,6 +3,16 @@ class Order < ApplicationRecord
   DRAFT_EXPIRY_TIME = 15.minutes
   MAX_PAYMENT_ATTEMPTS = 3
 
+  # === Enums ===
+  enum :status, {
+    draft: 0,
+    pending_payment: 1,
+    paid: 2,
+    completed: 3,
+    cancelled: 4,
+    expired: 5
+  }, default: :draft
+
   # === Associations ===
   belongs_to :user
   belongs_to :event
@@ -23,8 +33,9 @@ class Order < ApplicationRecord
   attr_accessor :stripe_invoice_id
 
   # === Scopes ===
-  scope :draft, -> { where(status: "draft") }
-  scope :active, -> { where(status: %w[paid completed]) }
+  scope :draft, -> { where(status: :draft) }
+  scope :active, -> { where(status: [ :paid, :completed ]) }
+  scope :paid, -> { where(status: :paid) }
   scope :expired_drafts, -> { draft.where("expires_at < ?", Time.current) }
   scope :can_retry_payment, -> {
     draft.where("payment_attempts < ? AND expires_at > ?",