Both guards were fully implemented but never actually wired in -- Nest
doesn't enforce a guard just because its module is imported, it needs
an explicit APP_GUARD registration. Registered both globally so every
new controller is deny-by-default and rate-limited unless it opts out.
Added a @Public() decorator (checked via Reflector in TenantGuard) for
routes that legitimately have no session, applied it to /health so the
global guard doesn't break it.
CORS was wide open (enableCors() with no origin restriction, effectively
allow-any-origin). Now reads an explicit CORS_ORIGINS allowlist from env,
defaulting to localhost:3000 for local dev.
