Fixed: the customer portal no longer crashes when a browser blocks website data

A customer whose browser blocks website data, common with strict privacy settings or certain browser extensions, used to hit a full-page error on every route of the subscription portal, including the login screen and the subscriptions list.

The portal now treats blocked storage the same as no active session: instead of crashing, it shows the normal logged-out portal, and the customer can proceed from there. The checks that look for a saved session are now guarded so a storage error doesn't throw partway through the page; the customer is sent to the login page rather than left on a failed page with no way forward.

Logging in still requires storage to work, since a session can't be created without it, so this fix addresses the crash specifically rather than signing in with storage fully blocked. It removes a dead end that previously affected every route in the portal.