feat: complete promoter payout system with Stripe Connect onboarding

app/services/stripe_connect_service.rb

@@ -0,0 +1,35 @@
+class StripeConnectService
+  def self.create_account(user)
+    return if user.stripe_connected_account_id.present?
+
+    account = Stripe::Account.create(
+      type: 'express',
+      country: 'FR',
+      email: user.email,
+      capabilities: {
+        card_payments: {requested: true},
+        transfers: {requested: true}
+      }
+    )
+    
+    user.update!(stripe_connected_account_id: account.id)
+    account
+  end
+
+  def self.onboarding_link(user)
+    return unless user.stripe_connected_account_id.present?
+
+    account_link = Stripe::AccountLink.create(
+      account: user.stripe_connected_account_id,
+      refresh_url: Rails.application.routes.url_helpers.promoter_stripe_refresh_url,
+      return_url: Rails.application.routes.url_helpers.promoter_stripe_return_url,
+      type: 'account_onboarding'
+    )
+    
+    account_link.url
+  end
+
+  def self.get_account_details(account_id)
+    Stripe::Account.retrieve(account_id)
+  end
+end