feat(docker): PostgreSQL 每日自动备份

- 新增 backup.sh: pg_dump + gzip，自动清理过期备份
- production compose 添加 backup 服务: cron 每日 02:00 执行
- 可通过 BACKUP_CRON / BACKUP_KEEP_DAYS 环境变量自定义

docker/backup.sh

@@ -0,0 +1,43 @@
+#!/usr/bin/env bash
+# PostgreSQL 自动备份脚本
+# 用法:
+#   手动: ./docker/backup.sh
+#   自动: 由 docker compose backup 服务每日 02:00 执行
+set -euo pipefail
+
+BACKUP_DIR="${BACKUP_DIR:-/backups}"
+PG_HOST="${PGHOST:-postgres}"
+PG_PORT="${PGPORT:-5432}"
+PG_USER="${PGUSER:-erp}"
+PG_DB="${PGDATABSE:-erp}"
+KEEP_DAYS="${KEEP_DAYS:-7}"
+TIMESTAMP=$(date +%Y%m%d_%H%M%S)
+FILENAME="${PG_DB}_${TIMESTAMP}.sql.gz"
+FILEPATH="${BACKUP_DIR}/${FILENAME}"
+
+mkdir -p "${BACKUP_DIR}"
+
+echo "[$(date -Iseconds)] 开始备份 ${PG_DB} → ${FILEPATH}"
+
+if pg_dump \
+    -h "${PG_HOST}" \
+    -p "${PG_PORT}" \
+    -U "${PG_USER}" \
+    -d "${PG_DB}" \
+    --format=plain \
+    --no-owner \
+    --no-privileges \
+    | gzip > "${FILEPATH}"; then
+    SIZE=$(du -h "${FILEPATH}" | cut -f1)
+    echo "[$(date -Iseconds)] 备份完成: ${FILENAME} (${SIZE})"
+else
+    echo "[$(date -Iseconds)] 备份失败！" >&2
+    rm -f "${FILEPATH}"
+    exit 1
+fi
+
+# 清理过期备份
+DELETED=$(find "${BACKUP_DIR}" -name "${PG_DB}_*.sql.gz" -mtime +${KEEP_DAYS} -delete -print | wc -l)
+if [ "${DELETED}" -gt 0 ]; then
+    echo "[$(date -Iseconds)] 已清理 ${DELETED} 个过期备份（>${KEEP_DAYS}天）"
+fi