Add SimpleFin controllers and routing

- Create SimplefinItemsController with CRUD operations
- Add account setup flow with user type selection
- Include sync management and error handling
- Update AccountsController to display SimpleFin items
- Add routes for SimpleFin item management and setup

app/controllers/accounts_controller.rb

@@ -5,6 +5,7 @@ class AccountsController < ApplicationController
   def index
     @manual_accounts = family.accounts.manual.alphabetically
     @plaid_items = family.plaid_items.ordered
+    @simplefin_items = family.simplefin_items.ordered
 
     render layout: "settings"
   end