feat: Implement event image upload system for promoters

- Add Active Storage migrations for file attachments
- Update Event model to handle image uploads with validation
- Replace image URL fields with file upload in forms
- Add client-side image preview with validation
- Update all views to display uploaded images properly
- Fix JSON serialization to prevent stack overflow in API
- Add custom image validation methods for format and size
- Include image processing variants for different display sizes
- Fix promotion code test infrastructure and Stripe configuration

🤖 Generated with [Claude Code](https://claude.com/claude-code)

Co-Authored-By: Claude <noreply@anthropic.com>

test/controllers/orders_controller_promotion_test.rb

@@ -1,4 +1,5 @@
 require "test_helper"
+require "securerandom"
 
 class OrdersControllerPromotionTest < ActionDispatch::IntegrationTest
   include Devise::Test::IntegrationHelpers
@@ -7,7 +8,8 @@ class OrdersControllerPromotionTest < ActionDispatch::IntegrationTest
   def setup
     @user = users(:one)
     @event = events(:concert_event)
-    @order = orders(:draft_order)
+    # Create a new order for the test to ensure proper associations
+    @order = @user.orders.create!(event: @event, status: "draft", expires_at: 15.minutes.from_now, total_amount_cents: 2000)
     sign_in @user
   end
 
@@ -25,19 +27,27 @@ class OrdersControllerPromotionTest < ActionDispatch::IntegrationTest
       event: @event
     )
 
-    Ticket.create!(
+    ticket = Ticket.create!(
       order: @order,
       ticket_type: ticket_type,
       status: "draft",
       first_name: "John",
-      last_name: "Doe"
+      last_name: "Doe",
+      price_cents: 2000
     )
 
+    # Debug the ticket creation
+    puts "Ticket saved: #{ticket.persisted?}"
+    puts "Ticket errors: #{ticket.errors.full_messages}" unless ticket.valid?
+    puts "Order tickets count: #{@order.tickets.count}"
+
     # Recalculate the order total
     @order.calculate_total!
 
+    # Use a unique code for each test run
+    unique_code = "TESTDISCOUNT_#{SecureRandom.hex(4)}"
     promotion_code = PromotionCode.create(
-      code: "TESTDISCOUNT",
+      code: unique_code,
       discount_amount_cents: 500, # €5.00
       expires_at: 1.month.from_now,
       active: true,
@@ -45,7 +55,9 @@ class OrdersControllerPromotionTest < ActionDispatch::IntegrationTest
       event: @event
     )
 
-    get checkout_order_path(@order), params: { promotion_code: "TESTDISCOUNT" }
+    get checkout_order_path(@order), params: { promotion_code: unique_code }
+    puts "Response status: #{response.status}"
+    puts "Response body: #{response.body}" if response.status != 200
     assert_response :success
     assert_not_nil flash.now[:notice]
     assert_match /Code promotionnel appliqué: TESTDISCOUNT/, flash.now[:notice]