docs(pgdb): compose 开机竞态故障修复 + 自愈 unit (W1N-260)

- 根因：开机时 docker 恢复容器绑定 192.168.55.15:5432/8081 失败（EADDRNOTAVAIL，IP 尚未可绑）→ timescaledb/pgweb 启动失败且不重试，停摆 3h15m；pg-backup 开机备份失败 → unhealthy
- 处置：docker compose up -d --force-recreate（三容器回 database_default、端口发布、备份恢复、pgweb 恢复）；用户重启 HA Core 后写入管道恢复
- 防复发：新增开机自愈 systemd oneshot pgdb-compose.service（enabled），源码 compose/pgdb/pgdb-compose.service

compose/pgdb/pgdb-compose.service

@@ -0,0 +1,24 @@
+[Unit]
+Description=Reconcile pgdb compose stack (timescaledb + pgweb + pg-backup) at boot
+Documentation=file:///opt/database/docker-compose.yml
+After=network-online.target docker.service
+Wants=network-online.target
+Requires=docker.service
+
+[Service]
+Type=oneshot
+RemainAfterExit=yes
+WorkingDirectory=/opt/database
+# Idempotent boot-time reconcile. docker's own restore can fail to bind the
+# published ports (192.168.55.15:5432/8081) when the VM IP is not yet usable
+# right after boot (EADDRNOTAVAIL, observed 2026-08-30): timescaledb/pgweb
+# then stay stopped until a manual `docker compose up`. This unit retries
+# `docker compose up -d` (a no-op when the stack is healthy) until the port
+# listens, and force-recreates as a last resort to recover a network-detached
+# container. Data lives on bind mounts (/srv/pgdata, /opt/database/backups),
+# so recreation is safe.
+ExecStart=/bin/bash -c 'for i in $(seq 1 12); do docker compose up -d --remove-orphans; sleep 2; if ss -tln | grep -q "192.168.55.15:5432"; then exit 0; fi; sleep 3; done; echo "pgdb-compose: retries exhausted, force-recreating"; docker compose up -d --force-recreate; sleep 10; ss -tln | grep -q "192.168.55.15:5432"'
+TimeoutStartSec=180
+
+[Install]
+WantedBy=multi-user.target