Add OIDC fixes, add prefered_username, add application-user claims

db/migrate/20251125012446_add_username_to_users.rb

@@ -0,0 +1,6 @@
+class AddUsernameToUsers < ActiveRecord::Migration[8.1]
+  def change
+    add_column :users, :username, :string
+    add_index :users, :username, unique: true
+  end
+end