docs(readme): document maintenance mode and migration path

README.md

@@ -2,6 +2,8 @@
 
 [中文文档](README_CN.md)
 
+> **Maintenance status**: CPA-Manager is now in maintenance mode. Future work is limited to security maintenance and bug fixes. For new deployments, feature upgrades, and long-term use, migrate to [CPA Manager Plus](https://github.com/seakee/CPA-Manager-Plus). See the [migration guide](https://github.com/seakee/CPA-Manager-Plus/blob/main/docs/migration-from-cpa-manager.md) when upgrading from this project.
+
 A single-file Web UI for **CLI Proxy API (CPA)** plus an optional **Usage Service** for persistent usage analytics.
 
 **Main Project**: https://github.com/router-for-me/CLIProxyAPI  
@@ -89,6 +91,8 @@ Use this when CPA still auto-downloads and serves the panel. This mode is served
 
 ## Quick Start: Full Docker Mode
 
+> For new deployments, use [CPA Manager Plus](https://github.com/seakee/CPA-Manager-Plus). The CPA-Manager deployment steps below are kept for users who still need to maintain existing installations.
+
 ### Docker Hub Image
 
 ```bash
@@ -362,6 +366,8 @@ go run ./cmd/cpa-manager
 
 ## Build and Release
 
+> Maintenance policy: CPA-Manager no longer plans feature releases. Except for security maintenance and bug fixes, release and upgrade work should move to [CPA Manager Plus](https://github.com/seakee/CPA-Manager-Plus).
+
 - Vite builds a single-file `dist/index.html`.
 - Tagging `vX.Y.Z` triggers `.github/workflows/release.yml`.
 - The release workflow uploads `dist/management.html`, native packages, and `checksums.txt` to GitHub Releases.
@@ -420,6 +426,8 @@ The UI language is automatically detected from browser settings and can be manua
 
 ## References
 
+- CPA Manager Plus: https://github.com/seakee/CPA-Manager-Plus
+- Migration from CPA-Manager to CPA Manager Plus: https://github.com/seakee/CPA-Manager-Plus/blob/main/docs/migration-from-cpa-manager.md
 - CPA-Manager Wiki: https://github.com/seakee/CPA-Manager/wiki
 - Docker deployment guide: https://github.com/seakee/CPA-Manager/wiki/Docker-Deployment
 - Usage Service guide: https://github.com/seakee/CPA-Manager/wiki/CPA%E2%80%90Manager-Usage-Service-Guide

README_CN.md

@@ -2,6 +2,8 @@
 
 [English](README.md)
 
+> **维护状态**：CPA-Manager 已进入维护模式，后续仅做安全维护和 bug 修复。新部署、功能升级和长期使用建议迁移到 [CPA Manager Plus](https://github.com/seakee/CPA-Manager-Plus)。从旧项目升级请参考 [迁移指南](https://github.com/seakee/CPA-Manager-Plus/blob/main/docs/migration-from-cpa-manager.zh-CN.md)。
+
 这是面向 **CLI Proxy API（CPA）** 的单文件 Web 管理面板，并提供可选的 **Usage Service** 用于持久化请求统计。
 
 CPA 自 v6.10.0 起不再内置用量统计。当前方案通过常驻 Usage Service 消费 CPA 的用量队列，把请求级事件写入 SQLite，并向面板提供兼容的用量查询接口。
@@ -85,6 +87,8 @@ Usage Service
 
 ## 快速开始：完整 Docker 方案
 
+> 新部署请优先使用 [CPA Manager Plus](https://github.com/seakee/CPA-Manager-Plus)。以下 CPA-Manager 部署步骤仅供仍需维护旧实例的用户参考。
+
 ### Docker Hub 镜像
 
 ```bash
@@ -358,6 +362,8 @@ go run ./cmd/cpa-manager
 
 ## 构建与发布
 
+> 维护策略：CPA-Manager 不再规划功能发布；除安全维护和 bug 修复外，请将发布和升级工作转向 [CPA Manager Plus](https://github.com/seakee/CPA-Manager-Plus)。
+
 - Vite 输出单文件 `dist/index.html`
 - 打 `vX.Y.Z` 标签会触发 `.github/workflows/release.yml`
 - 发布流程会上传 `dist/management.html`、原生运行包和 `checksums.txt` 到 GitHub Releases
@@ -416,6 +422,8 @@ go run ./cmd/cpa-manager
 
 ## 参考
 
+- CPA Manager Plus: https://github.com/seakee/CPA-Manager-Plus
+- CPA-Manager 到 CPA Manager Plus 迁移指南: https://github.com/seakee/CPA-Manager-Plus/blob/main/docs/migration-from-cpa-manager.zh-CN.md
 - CPA-Manager Wiki: https://github.com/seakee/CPA-Manager/wiki
 - Docker 部署指南: https://github.com/seakee/CPA-Manager/wiki/Docker-%E9%83%A8%E7%BD%B2-CPA%E2%80%90Manager
 - Usage Service 使用指南: https://github.com/seakee/CPA-Manager/wiki/CPA%E2%80%90Manager-Usage-Service-%E4%BD%BF%E7%94%A8%E6%8C%87%E5%8D%97