release: 1.9.1: Port-25 Postfix startup with inbound/DMARC/antispam flags

Port-25 Postfix startup when inbound relay, DMARC ingest, or the inbound antispam milter are enabled. Schema-migration reference and roadmap plans for inbound antispam and quarantine. Upgrading from 1.9.0 is a tag bump; no migration.
Added:
  - [docs/plans/inbound-antispam-panel.md](docs/plans/inbound-antispam-panel.md) —
  - [docs/plans/inbound-quarantine.md](docs/plans/inbound-quarantine.md) — candidate
  - [docs/schema-migrations.md](docs/schema-migrations.md) — living reference for the
Changed:
  - [docs/roadmap.md](docs/roadmap.md) — `inbound-antispam-panel` (agreed, 1/12)
  - [docs/development.md](docs/development.md) — plan checklists may override
  - [docs/development.md](docs/development.md), [docs/roadmap.md](docs/roadmap.md),
Fixed:
  - `build/postfix-config.sh`: enabling inbound relay, DMARC ingest, and/or the

Full detail: CHANGELOG.md (1.9.1).

deploy/docker-compose.yml

@@ -22,7 +22,7 @@
 
 services:
   selfpost:
-    image: ghcr.io/mixeme/selfpost:1.9.0
+    image: ghcr.io/mixeme/selfpost:1.9.1
     restart: unless-stopped
     environment:
       SELFPOST_HOSTNAME: "${SELFPOST_HOSTNAME:?set the mail/panel hostname, e.g. mail.example.com}"