docs(readme): update Kimi sponsor copy to K2.7 Code

Refresh the Kimi sponsor blurb to the K2.7 Code release (coding-focused
agentic model, ~30% lower thinking-token usage vs K2.6) and bump the
banner alt text from K2.6 to K2.7 Code. EN/ZH copy provided by the
vendor; JA/DE translated to match.

README.md

@@ -25,9 +25,9 @@ English | [中文](README_ZH.md) | [日本語](README_JA.md) | [Deutsch](README_
 <details open>
 <summary>Click to collapse</summary>
 
-[![Kimi K2.6](assets/partners/banners/kimi-banner-en.png)](https://platform.moonshot.cn/console?aff=cc-switch)
+[![Kimi K2.7 Code](assets/partners/banners/kimi-banner-en.png)](https://platform.moonshot.cn/console?aff=cc-switch)
 
-Kimi K2.6 is an open-source, native multimodal agentic model from Moonshot AI, built for long-horizon coding, coding-driven design, and swarm-based task orchestration. It is designed to handle complex end-to-end engineering work across front-end, DevOps, performance optimization, and full-stack workflows, while coordinating large groups of specialized agents to plan, implement, test, and iterate on real coding tasks. **[Click here to start using Kimi](https://platform.moonshot.cn/console?aff=cc-switch)**
+Kimi K2.7 Code is an open-source, coding-focused agentic model developed by Moonshot AI. It delivers stronger coding and agent performance, with substantial improvements in real-world long-horizon coding tasks. These gains translate into higher end-to-end task success rates across complex software engineering workflows. K2.7 Code also improves reasoning efficiency, reducing thinking-token usage by approximately 30% compared with K2.6. **[Click here to start using Kimi](https://platform.moonshot.cn/console?aff=cc-switch)**
 
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