jsonResponse() was defined at module scope but referenced `url` which
only existed as a parameter of handleCookiePickerRoute(). Every API call
crashed, the catch block also crashed, and Bun returned a default HTML
page that the frontend couldn't parse as JSON.
Thread port via corsOrigin() helper and options objects. Add route-level
tests to prevent this class of bug from shipping again.
Co-Authored-By: Claude Opus 4.6 <noreply@anthropic.com>
