feat: Graceful shutdown (10s)；backup 格式兼容 .dump.gz；容器连接监控

lib/common.sh

@@ -279,8 +279,8 @@ backup_database() {
 }
 
 cleanup_old_db_backups() {
-    local keep="${1:-1}"
-    local to_del; to_del=$(remote "ls -t ${REMOTE_DIR}/backups/${DB_NAME}_*.dump 2>/dev/null | tail -n +$((keep+1))" || echo "")
+    local keep="${1:-7}"
+    local to_del; to_del=$(remote "ls -t ${REMOTE_DIR}/backups/${DB_NAME}_*.dump* 2>/dev/null | tail -n +$((keep+1))" || echo "")
     [ -z "$to_del" ] && return 0
     log_step "清理旧数据库备份（保留 ${keep} 个）..."
     echo "$to_del" | while read -r f; do [ -n "$f" ] && remote "rm -f '${f}'" 2>/dev/null && echo "  删除: $(basename "$f")" || true; done