docs: update Chinese README and move language link to badge row

Move the language switcher from above the logo into the badge row
alongside Discord. Update README_zh.md to match current English
README: add Agent Swarms announcement and feature, update
architecture section with all key files, add Community section,
and fix file descriptions.

Co-Authored-By: Claude Opus 4.6 <noreply@anthropic.com>

README.md

@@ -1,7 +1,3 @@
-<p align="center">
-  <b>English</b> | <a href="README_zh.md">中文</a>
-</p>
-
 <p align="center">
   <img src="assets/nanoclaw-logo.png" alt="NanoClaw" width="400">
 </p>
@@ -11,6 +7,7 @@
 </p>
 
 <p align="center">
+  <a href="README_zh.md">中文</a> ·
   <a href="https://discord.gg/VGWXrf8x"><img src="https://img.shields.io/discord/1470188214710046894?label=Discord&logo=discord&v=2" alt="Discord"></a>
 </p>