fix(badge): switch star badge to flat-square + short cache to avoid shields.io token-pool errors

shields.io's 'social' style badge intermittently fails with 'Unable to select
next GitHub token from pool' when their token bucket is exhausted, and the
GitHub camo proxy then caches the error response. Switching to flat-square
with explicit label and shorter cache (300s) makes failures self-heal.

Author: Zijian-Ni

README.ja.md

@@ -3,7 +3,7 @@
 # 🤖 Awesome AI Agents 2026 · 日本語版
 
 [![Awesome](https://awesome.re/badge.svg)](https://awesome.re)
-[![GitHub stars](https://img.shields.io/github/stars/Zijian-Ni/awesome-ai-agents-2026?style=social)](https://github.com/Zijian-Ni/awesome-ai-agents-2026)
+[![GitHub stars](https://img.shields.io/github/stars/Zijian-Ni/awesome-ai-agents-2026?style=flat-square&label=★%20Stars&color=yellow&cacheSeconds=300)](https://github.com/Zijian-Ni/awesome-ai-agents-2026/stargazers)
 [![License: MIT](https://img.shields.io/badge/License-MIT-yellow.svg)](https://opensource.org/licenses/MIT)
 [![PRs Welcome](https://img.shields.io/badge/PRs-welcome-brightgreen.svg)](CONTRIBUTING.md)
 [![Last Updated](https://img.shields.io/badge/Last%20Updated-June%209%2C%202026-blue.svg)](#)

README.md

@@ -3,7 +3,7 @@
 # 🤖 Awesome AI Agents 2026
 
 [![Awesome](https://awesome.re/badge.svg)](https://awesome.re)
-[![GitHub stars](https://img.shields.io/github/stars/Zijian-Ni/awesome-ai-agents-2026?style=social)](https://github.com/Zijian-Ni/awesome-ai-agents-2026)
+[![GitHub stars](https://img.shields.io/github/stars/Zijian-Ni/awesome-ai-agents-2026?style=flat-square&label=★%20Stars&color=yellow&cacheSeconds=300)](https://github.com/Zijian-Ni/awesome-ai-agents-2026/stargazers)
 [![License: MIT](https://img.shields.io/badge/License-MIT-yellow.svg)](https://opensource.org/licenses/MIT)
 [![PRs Welcome](https://img.shields.io/badge/PRs-welcome-brightgreen.svg)](CONTRIBUTING.md)
 [![Last Updated](https://img.shields.io/badge/Last%20Updated-June%209%2C%202026-blue.svg)](#)

README.zh-CN.md

@@ -3,7 +3,7 @@
 # 🤖 Awesome AI Agents 2026 · 中文版
 
 [![Awesome](https://awesome.re/badge.svg)](https://awesome.re)
-[![GitHub stars](https://img.shields.io/github/stars/Zijian-Ni/awesome-ai-agents-2026?style=social)](https://github.com/Zijian-Ni/awesome-ai-agents-2026)
+[![GitHub stars](https://img.shields.io/github/stars/Zijian-Ni/awesome-ai-agents-2026?style=flat-square&label=★%20Stars&color=yellow&cacheSeconds=300)](https://github.com/Zijian-Ni/awesome-ai-agents-2026/stargazers)
 [![License: MIT](https://img.shields.io/badge/License-MIT-yellow.svg)](https://opensource.org/licenses/MIT)
 [![PRs Welcome](https://img.shields.io/badge/PRs-welcome-brightgreen.svg)](CONTRIBUTING.md)
 [![Last Updated](https://img.shields.io/badge/Last%20Updated-June%209%2C%202026-blue.svg)](#)