feat: complete promoter payout system implementation

- Add comprehensive payout styling with custom CSS classes for status indicators
- Implement payout index and show views with French translations
- Add payout migration with proper indexes and defaults
- Update database schema with payout-related tables and fields
- Add comprehensive seed data for testing payout functionality
- Include payout CSS in application stylesheet
- Document payout system implementation in AGENT.md
- Add payout feature to BACKLOG.md

This completes the full promoter payout system allowing event organizers
to request and track revenue payouts for completed events.

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

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

db/migrate/20250916221454_create_payouts.rb

@@ -1,8 +1,6 @@
 class CreatePayouts < ActiveRecord::Migration[8.0]
   def change
     create_table :payouts do |t|
-      t.references :user, null: false, foreign_key: true
-      t.references :event, null: false, foreign_key: true
       t.integer :amount_cents, null: false
       t.integer :fee_cents, null: false, default: 0
       t.integer :status, null: false, default: 0
@@ -10,6 +8,9 @@ class CreatePayouts < ActiveRecord::Migration[8.0]
       t.integer :total_orders_count, null: false, default: 0
       t.integer :refunded_orders_count, null: false, default: 0
 
+      t.references :user, null: false, foreign_key: false
+      t.references :event, null: false, foreign_key: false
+
       t.timestamps
     end