UR-Nexus 1.68.7

• Corrected the ur.ai -> ur.com replacement, which had rewritten identifiers as
  well as URLs. 'ur.ai' served two roles in this codebase: a domain in links
  such as https://ur.ai/settings/billing, and a discriminant value in
  authTokenSource === 'ur.ai', authMethod = 'ur.ai' and
  source: 'ur.ai' as const. A blanket replace changed both, which typechecked
  and looked internally consistent but altered command availability — one
  command that should have been hidden became visible, caught by
  commandRegistryIntegrity. The 39 URLs now point at ur.com; the 11 auth
  discriminants are back to their original values, which also keeps any
  "ur.ai" already persisted in a user's auth state matching.