Update community group QR code

Author: jackjls

README.md

@@ -383,11 +383,11 @@ src/ftshare/
 
 欢迎加入 FTShare 社区交流群，一起讨论 Python SDK 使用、接口问题、数据接入、量化研究和 Agent / MCP / Skill 相关实践。
 
-<img src="docs/assets/wechat-group-20260826.png" alt="FTShare 微信交流群" width="320" />
+<img src="docs/assets/wechat-group-20260902.png" alt="FTShare 微信交流群" width="320" />
 
 > **群规说明**：
 > - 仅限 FTShare 项目、金融数据接口、Python SDK、MCP、Skill 和 Agent 使用相关讨论
 > - 禁止广告、推广、无关闲聊
 > - Bug、功能需求和接口问题，建议优先在 GitHub Issues 中提交，群内用于快速交流和补充说明
 
-**二维码有效期至 2026 年 8 月 26 日。** 如二维码失效，请在 Issues 中留言，维护者会更新入群方式。
+**二维码有效期至 2026 年 9 月 2 日。** 如二维码失效，请在 Issues 中留言，维护者会更新入群方式。

README_EN.md

@@ -385,11 +385,11 @@ src/ftshare/
 
 Chinese users are welcome to join the FTShare WeChat community group to discuss SDK usage, interface issues, data access, quantitative research, and Agent / MCP / Skill practices.
 
-<img src="docs/assets/wechat-group-20260826.png" alt="FTShare WeChat community group" width="320" />
+<img src="docs/assets/wechat-group-20260902.png" alt="FTShare WeChat community group" width="320" />
 
 > **Community rules**:
 > - Discussions should be related to FTShare, financial data interfaces, the Python SDK, MCP, Skills, or Agent usage
 > - Advertising, promotion, and unrelated off-topic chat are not allowed
 > - For bugs, feature requests, and interface issues, please open a GitHub Issue first. The group is for quick discussion and follow-up context
 
-**The QR code is valid until August 26, 2026.** If it expires, please open an Issue and the maintainers will update the invitation.
+**The QR code is valid until September 2, 2026.** If it expires, please open an Issue and the maintainers will update the invitation.