The grand tunnel restructuring removed the CLI's auto-generated UI
password, so `openchamber -d --ui-password` (no value) silently started
an unauthenticated server instead of creating a password as in 1.8.1.
Restore generation for an explicit --ui-password flag without a value:
the password is generated before either launch path, passed to the
daemon/foreground process via OPENCHAMBER_UI_PASSWORD, persisted in the
instance state file, and surfaced once in human/quiet/json output.
Refs OPE-216
Serhii Dziupin