Fix common B2B access and permission issues

If a user sees Unauthorized

1. Check their organization role first.
2. Check invitation acceptance and active membership status.
3. Ask the user to sign out, sign in, and refresh once.

If invitation acceptance fails

1. Check invitation expiry and invited email match.
2. Check available student seats for student invitations.
3. Resend invitation if needed.

If modules or stations are missing

1. Confirm module status is Published.
2. Confirm station status is Published.
3. Confirm the module is visible to that organization.

If students cannot join cohorts

1. Confirm user role is STUDENT.
2. Confirm organization membership is ACTIVE.
3. Retry from cohort detail page and capture exact error text if it fails again.