fix(install): 向导守护 UI 与升级后 cron 交互提示

Docker 完成页展示 Layer 3 cron 步骤与 host_deploy_root；TTY 下 nx update 可一键安装巡检/备份 crontab。

Co-authored-by: Cursor <cursoragent@cursor.com>

server/api/install.py

@@ -863,6 +863,7 @@ _INSTALL_STATE_PUBLIC_KEYS = frozenset({
     "pool_size",
     "max_overflow",
     "install_dir",
+    "host_deploy_root",
     "docker_mode",
     "guardian_results",
     "installed",
@@ -1261,6 +1262,7 @@ async def init_db(req: InitDbRequest):
 
     # Configure process guardian (best-effort)
     install_dir = str(ROOT_DIR)
+    host_deploy_root = _host_deploy_root(install_dir)
     guardian_results = _configure_guardian(install_dir, req.api_port)
 
     # Save install state for step 4
@@ -1277,6 +1279,7 @@ async def init_db(req: InitDbRequest):
         "pool_size": pool_size,
         "max_overflow": max_overflow,
         "install_dir": install_dir,
+        "host_deploy_root": host_deploy_root,
         "site_url": site_url,
         "api_port": req.api_port,
         "redis_host": req.redis_host,
@@ -1297,6 +1300,7 @@ async def init_db(req: InitDbRequest):
         "max_overflow": max_overflow,
         "tables_created": 14,
         "guardian_results": guardian_results,
+        "host_deploy_root": host_deploy_root,
         "bt_panel": _detect_bt_panel(),
         "docker_mode": _is_docker_install_mode(),
     }