v1.0.0 — platform + packages + mail in one flow

First complete release of the installer: stages 0-8 deploy a BPMSoft
instance end to end on a clean Ubuntu VM — system components, the
distribution, the database, configs and systemd, package auto-install
(stage 7), and the mail module (stage 8: Exchange Listener stack +
wiring mail into BPMSoft). Online or fully air-gapped, idempotent,
with dry-run, co-tenancy guard, smoke checks and an instance passport.