docs: update WeChat group QR to group 14, remove old group 13 image

README.md

@@ -207,7 +207,7 @@ You're also welcome to join our **GenericAgent Community Group** for discussion,
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-      <td align="center"><strong>WeChat Group 13</strong><br><img src="assets/images/wechat_group13.jpg" alt="WeChat Group 13 QR Code" width="250"/></td>
+      <td align="center"><strong>WeChat Group 14</strong><br><img src="assets/images/wechat_group14.jpg" alt="WeChat Group 14 QR Code" width="250"/></td>
     </tr>
   </table>
 </div>
@@ -492,7 +492,7 @@ GenericAgent 通过**分层记忆 × 最小工具集 × 自主执行循环**完
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-      <td align="center"><strong>微信群 13</strong><br><img src="assets/images/wechat_group13.jpg" alt="微信群 13 二维码" width="250"/></td>
+      <td align="center"><strong>微信群 14</strong><br><img src="assets/images/wechat_group14.jpg" alt="微信群 14 二维码" width="250"/></td>
     </tr>
   </table>
 </div>