add logo with light color and add it at README

Author: xueyulinn

README.md

@@ -1,7 +1,9 @@
-# CodeHawk
+<p align="center">
+  <img src="codehawk/static/assets/codehawk_light_logo.png" alt="CodeHawk logo" width="400">
+</p>
 
 <p align="center">
-  <img src="codehawk/static/assets/codehawk_logo.png" alt="CodeHawk logo" width="400">
+  AI-assisted code review for GitHub pull requests.
 </p>
 
 CodeHawk is an AI-assisted code review platform for GitHub pull requests. It receives GitHub App webhook events, fetches pull request context, runs repository indexing and static analysis jobs, and posts reviewer-focused summaries or code review comments back to GitHub.

README.zh-CN.md

@@ -1,7 +1,9 @@
-# CodeHawk
+<p align="center">
+  <img src="codehawk/static/assets/codehawk_light_logo.png" alt="CodeHawk logo" width="400">
+</p>
 
 <p align="center">
-  <img src="codehawk/static/assets/codehawk_logo.png" alt="CodeHawk logo" width="400">
+  面向 GitHub Pull Request 的 AI 辅助代码审查平台。
 </p>
 
 CodeHawk 是一个面向 GitHub Pull Request 的 AI 辅助代码审查平台。它接收 GitHub App webhook 事件，获取 PR 上下文，执行代码索引和静态分析任务，并将 PR 摘要或代码审查结果写回 GitHub。