audit-7 + docs: plan systemd units, D13-D15

- cayce-ops-plan.service/.timer (daily): the @ template cannot express
  publisher plan, so it gets its own unit
- DECISIONS: D13 no non-human approvals; D14 signatures bind content +
  deployment; D15 negation veto classifier

deploy/systemd/cayce-ops-plan.service

@@ -0,0 +1,15 @@
+[Unit]
+Description=cayce-ops publisher plan (fills the content calendar, daily)
+After=network-online.target postgresql.service
+Wants=network-online.target
+
+[Service]
+Type=oneshot
+User=cayce
+WorkingDirectory=/srv/cayce-ops
+EnvironmentFile=/srv/cayce-ops/.env
+ExecStart=/srv/cayce-ops/.venv/bin/cayceops publisher plan
+NoNewPrivileges=yes
+ProtectSystem=strict
+ProtectHome=yes
+ReadWritePaths=/srv/cayce-ops

deploy/systemd/cayce-ops-plan.timer

@@ -0,0 +1,10 @@
+[Unit]
+Description=Run cayce-ops publisher plan daily
+
+[Timer]
+OnCalendar=*-*-* 06:00:00
+RandomizedDelaySec=300
+Persistent=true
+
+[Install]
+WantedBy=timers.target