AbstractContinuum 0.3.1

Compatibility: same as 0.3.0 (AbstractGateway 0.4.1 or newer). No
action is needed unless you relied on the Team page's old personal hub-seat
default: set your seat once — on the Settings page (Settings → Team (agora
hub) → Hub seat), with abstractcontinuum config set hub_seat <seat>, or
with --hub-seat <seat> for one run. Environment variables you already use
keep working as a legacy fallback.

Changed

• Continuum's server is configured with launch flags or
  abstractcontinuum config. Every server setting has a flag (--port,
  --host, --gateway-url, --hub-url, --hub-seat, --hub-token-file,
  --hub-allow-remote, the sign-in proxy settings, …) and a saved setting
  in ~/.abstractcontinuum/settings.json, written with
  abstractcontinuum config set <setting> <value> (config get shows every
  value and where it comes from). The file is owner-only because it can
  hold the hub token. Environment variables remain a legacy fallback.
• The hub seat is a setting on the Settings page (Settings → Team
  (agora hub) → Hub seat). It is saved on the Continuum server, survives
  restarts and applies to the Team page at once. You can also run
  abstractcontinuum config set hub_seat <seat>, or pass --hub-seat for
  one run.
• The Team page's hub seat defaults to operator instead of a personal
  name. If you used the Team page without choosing a seat, set yours as
  above.
• abstractcontinuum --help lists every flag with its default and its
  setting name.
• npm run dev serves on port 3002 (Continuum's port on the stack map),
  reads the same settings file, and proxies /api to the configured
  gateway.