Use playable README video preview

Replace the README video tag with a GitHub-rendered animated preview while keeping the MP4 link for audio playback.

Author: terrywangcode

README.md

@@ -5,11 +5,13 @@
 **An open-source control plane for governed agent systems.**
 
 <p align="center">
-  <video src="docs/assets/openhive-product-intro.mp4" controls playsinline width="100%" title="OpenHive product introduction"></video>
+  <a href="docs/assets/openhive-product-intro.mp4">
+    <img src="docs/assets/openhive-product-intro.gif" alt="OpenHive product introduction video preview" width="100%" />
+  </a>
 </p>
 
 <p align="center">
-  <a href="docs/assets/openhive-product-intro.mp4">Watch the OpenHive product intro video</a>
+  <a href="docs/assets/openhive-product-intro.mp4">Watch the OpenHive product intro video with audio</a>
 </p>
 
 OpenHive helps teams create, run, and govern agent systems with a clear path

README.zh-CN.md

@@ -7,11 +7,13 @@
 **一个面向受治理 Agent 系统的开源控制平面。**
 
 <p align="center">
-  <video src="docs/assets/openhive-product-intro.mp4" controls playsinline width="100%" title="OpenHive 产品介绍"></video>
+  <a href="docs/assets/openhive-product-intro.mp4">
+    <img src="docs/assets/openhive-product-intro.gif" alt="OpenHive 产品介绍视频预览" width="100%" />
+  </a>
 </p>
 
 <p align="center">
-  <a href="docs/assets/openhive-product-intro.mp4">观看 OpenHive 产品介绍视频</a>
+  <a href="docs/assets/openhive-product-intro.mp4">观看带声音的 OpenHive 产品介绍视频</a>
 </p>
 
 OpenHive 帮助团队创建、运行并治理 Agent 系统，并提供一条从本地预览走向面向生产