Fixed Rails route covering %40-encoded profile URL paths to not 404 (#31184)

config/routes.rb

@@ -142,7 +142,11 @@ Rails.application.routes.draw do
 
   resource :inbox, only: [:create], module: :activitypub
 
-  get '/:encoded_at(*path)', to: redirect('/@%{path}'), constraints: { encoded_at: /%40/ }
+  constraints(encoded_path: /%40.*/) do
+    get '/:encoded_path', to: redirect { |params|
+      "/#{params[:encoded_path].gsub('%40', '@')}"
+    }
+  end
 
   constraints(username: %r{[^@/.]+}) do
     with_options to: 'accounts#show' do