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

test/fixtures/events.yml

@@ -1,5 +1,19 @@
 # Read about fixtures at https://api.rubyonrails.org/classes/ActiveRecord/FixtureSet.html
 
+one:
+  name: Test Event
+  slug: test-event
+  description: This is a test event description that is long enough to meet validation requirements.
+  state: published
+  venue_name: Test Venue
+  venue_address: 123 Test Street
+  latitude: 48.8566
+  longitude: 2.3522
+  start_time: <%= 1.week.from_now %>
+  end_time: <%= 1.week.from_now + 4.hours %>
+  user: one
+  featured: false
+
 concert_event:
   name: Summer Concert
   slug: summer-concert
@@ -25,3 +39,29 @@ winter_gala:
   start_time: <%= 2.weeks.from_now %>
   end_time: <%= 2.weeks.from_now + 6.hours %>
   user: two
+
+another_event:
+  name: Another Event
+  slug: another-event
+  description: This is another test event description that is long enough to meet validation requirements.
+  state: published
+  venue_name: Another Venue
+  venue_address: 456 Test Street
+  latitude: 48.8566
+  longitude: 2.3522
+  start_time: <%= 1.week.ago %>
+  end_time: <%= 1.week.ago + 4.hours %>
+  user: one
+
+ineligible:
+  name: Ineligible Event
+  slug: ineligible-event
+  description: This is an ineligible test event description that is long enough to meet validation requirements.
+  state: draft
+  venue_name: Ineligible Venue
+  venue_address: 789 Test Street
+  latitude: 48.8566
+  longitude: 2.3522
+  start_time: <%= 1.week.from_now %>
+  end_time: <%= 1.week.from_now + 4.hours %>
+  user: one