Revert "Login Loop"

This reverts commit 16c6c28f07.

README.md

@@ -34,11 +34,6 @@ administrator. That account can sign in at `/manager/sign-in`, create
 businesses, edit their primary domains, and share the one-time owner setup
 link generated during provisioning.
 
-For an existing installation created before this platform/tenant split, the
-recorded `initialAdminUserId` account is allowed to sign in once and is
-promoted to the platform administrator. No other business owner can use that
-upgrade path.
-
 Business provisioning creates the tenant domain, settings, booking rules,
 opening hours, system roles, owner staff profile, and seven-day owner
 invitation in one transaction. The owner chooses a password through that