Fix: Add local: true to invitation form to prevent blank token error

Fixes the "Invitation token can't be blank" error that occurs when new
users accept email invitations and try to set their password.

Root cause: PR #6528 refactored form_for to form_with, but form_with
defaults to remote: true (AJAX submission). This causes the hidden
invitation_token field to not be properly submitted with the form.

Solution: Add local: true to the form_with helper to use standard form
submission instead of AJAX, ensuring the invitation_token is correctly
included in the POST data.

Related to PR #6528 (form helper refactor)

Author: compwron

app/views/devise/invitations/edit.html.erb

@@ -1,7 +1,7 @@
 <div class="password-box px-4 pb-3">
   <h2 class="my-3">Send invitation</h2>
 
-  <%= form_with(model: resource, as: resource_name, url: invitation_path(resource_name), html: {method: :put}) do |f| %>
+  <%= form_with(model: resource, as: resource_name, url: invitation_path(resource_name), local: true, html: {method: :put}) do |f| %>
     <%= render "/shared/error_messages", resource: resource %>
     <%= f.hidden_field :invitation_token, readonly: true %>