fix: remove legacy admin payout process route and reorganize routes

- Remove legacy 'process' route from admin payouts (conflicted with Ruby's process method)
- Reorganize admin routes to logical position with proper section comment
- Simplify admin payout routes to only include actual functionality
- Update admin controller tests to test approval workflow instead of legacy routes
- Add proper test setup with banking info and onboarding completion
- Improve test coverage for admin authentication and payout approval

This resolves admin controller test failures and removes unnecessary legacy code
since the application is not yet published.

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

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

config/routes.rb

@@ -1,16 +1,4 @@
 Rails.application.routes.draw do
-  namespace :admin do
-    resources :payouts, only: [ :index, :show ] do
-      member do
-        post :process          # Legacy route
-        post :approve
-        post :reject
-        post :mark_processing
-        post :mark_completed
-        post :mark_failed
-      end
-    end
-  end
   # Define your application routes per the DSL in https://guides.rubyonrails.org/routing.html
 
   # Reveal health status on /up that returns 200 if the app boots with no exceptions, otherwise 500.
@@ -107,6 +95,19 @@ Rails.application.routes.draw do
     end
   end
 
+  # === Administration ===
+  namespace :admin do
+    resources :payouts, only: [ :index, :show ] do
+      member do
+        post :approve
+        post :reject
+        post :mark_processing
+        post :mark_completed
+        post :mark_failed
+      end
+    end
+  end
+
   # API routes versioning
   namespace :api do
     namespace :v1 do