feat(agent99): bind host110 backup runtime deploy

scripts/backup/common.sh

@@ -1,5 +1,38 @@
-#\!/bin/bash
+#!/bin/bash
 # =============================================================================
+
+# Production backup entrypoints share this stable gate. Agent99 takes the
+# exclusive side while promoting a complete, digest-bound runtime bundle.
+acquire_backup_runtime_shared_lock() {
+    local caller_path="${BASH_SOURCE[1]:-${BASH_SOURCE[0]}}"
+    local lock_path="/tmp/agent99-host110-backup-runtime.lock"
+    case "${caller_path}" in
+        /backup/scripts/*) ;;
+        *) return 0 ;;
+    esac
+    [ "${BACKUP_RUNTIME_SHARED_LOCK_HELD:-0}" != "1" ] || return 0
+    command -v flock >/dev/null 2>&1 || {
+        echo "backup runtime gate unavailable: flock missing" >&2
+        return 69
+    }
+    [ ! -L "${lock_path}" ] || {
+        echo "backup runtime gate unsafe: lock is a symlink" >&2
+        return 69
+    }
+    (umask 077; : >> "${lock_path}") || return 69
+    [ -f "${lock_path}" ] && [ -O "${lock_path}" ] || return 69
+    exec 197>>"${lock_path}"
+    flock -s -w 60 197 || {
+        echo "backup runtime deployment is active; retry later" >&2
+        return 75
+    }
+    export BACKUP_RUNTIME_SHARED_LOCK_HELD=1
+}
+
+acquire_backup_runtime_shared_lock || {
+    runtime_lock_status=$?
+    return "${runtime_lock_status}" 2>/dev/null || exit "${runtime_lock_status}"
+}
 # WOOO AIOps - 備份共用函式庫
 # 版本: 1.0.0
 # 建立日期: 2026-03-12