Logto's login page references /assets/* which conflicts with the SPA's
assets at the same path. Using Host-based routing (auth.localhost) gives
Logto its own namespace - all paths on that subdomain go to Logto,
eliminating the conflict. *.localhost resolves to 127.0.0.1 and is a
secure context.
Co-Authored-By: Claude Opus 4.6 (1M context) <noreply@anthropic.com>