docs(readme): a Download for Mac button at the top of both READMEs

The only DMG link above the fold was a plain link in the sentence under the
install command, easy to read past. Both READMEs now open with a large
"Download for Mac" button right under the tagline, pointing at the latest
release's Codeman.dmg, with one line on what the app is.

Co-Authored-By: Claude Opus 5.5 <noreply@anthropic.com>

README.md

@@ -8,6 +8,12 @@
   <em>Claude Code &bull; OpenCode &bull; Codex &bull; Antigravity &bull; Gemini &bull; Pi &bull; Grok &bull; DeepSeek &bull; OMP &bull; Copilot &bull; Terminal - One Dashboard &bull; Any Device</em>
 </p>
 
+<p align="center">
+  <a href="https://github.com/Ark0N/Codeman/releases/latest/download/Codeman.dmg"><img src="https://img.shields.io/badge/Download_for_Mac-Codeman.dmg-2f6fe0?style=for-the-badge&logo=apple&logoColor=white&labelColor=000000" alt="Download Codeman for Mac (Codeman.dmg)" width="442"></a>
+  <br>
+  <sub>The native Mac app: signed and notarized, Apple Silicon and Intel, macOS 11.3 or later. <a href="#on-a-mac-the-codeman-app">What it does</a></sub>
+</p>
+
 <p align="center">
   <a href="https://opensource.org/licenses/MIT"><img src="https://img.shields.io/badge/License-MIT-1e3a5f?style=flat-square" alt="License: MIT"></a>
   <a href="https://nodejs.org/"><img src="https://img.shields.io/badge/Node.js-22%2B-22c55e?style=flat-square&logo=node.js&logoColor=white" alt="Node.js 22+"></a>

README.zh-CN.md

@@ -8,6 +8,12 @@
   <em>Claude Code &bull; OpenCode &bull; Codex &bull; Antigravity &bull; Gemini &bull; Pi &bull; Grok &bull; DeepSeek &bull; OMP &bull; Copilot &bull; 终端 —— 统一仪表盘 &bull; 任意设备</em>
 </p>
 
+<p align="center">
+  <a href="https://github.com/Ark0N/Codeman/releases/latest/download/Codeman.dmg"><img src="https://img.shields.io/badge/%E4%B8%8B%E8%BD%BD_Mac_%E7%89%88-Codeman.dmg-2f6fe0?style=for-the-badge&logo=apple&logoColor=white&labelColor=000000" alt="下载 Mac 版 Codeman（Codeman.dmg）" width="351"></a>
+  <br>
+  <sub>原生 Mac 应用：已签名并经过 Apple 公证，支持 Apple 芯片和 Intel，macOS 11.3 或更高版本。<a href="#在-mac-上codeman-应用">它能做什么</a></sub>
+</p>
+
 <p align="center">
   <a href="README.md">English</a> &bull; <strong>简体中文</strong>
 </p>