docs: refresh WeChat group QR code

[david6666666]

Purpose

Refresh docs/assets/WeChat.png with the updated vLLM router community group QR code supplied on September 11. The image displays an expiration date of September 18. Existing README links continue to use the same path.

Test Plan

• Compare the replacement image SHA-256 with the supplied source.
• Decode the image and check the repository's 1000 KB file-size limit.
• Run git diff --cached --check before committing and confirm only the requested image changes.

Test Result

All checks passed. The copied PNG matches the source exactly, decodes at 1203 × 1683 pixels, and is 230,333 bytes. Only docs/assets/WeChat.png changed. Application tests were not run for this image-only update; joining the group via WeChat was not tested.

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[chatgpt-codex-connector]

Codex Review Summary

This comment shows the latest Codex review activity on this pull request.

Review	Status	Commit	Review trigger
📝 Code Review	✅ Completed 2026-09-11T01:15:48.252608Z	223a9fc	PR opened

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