docs: center badges in two rows for cleaner layout

Author: lijunliu-gh

README.md

@@ -1,15 +1,18 @@
 # Auto PPT
 
-[![Release](https://img.shields.io/github/v/tag/lijunliu-gh/auto-ppt-engine?label=release&sort=semver)](https://github.com/lijunliu-gh/auto-ppt-engine/tags)
-[![License](https://img.shields.io/badge/license-MIT-blue.svg)](LICENSE)
-[![CI](https://img.shields.io/github/actions/workflow/status/lijunliu-gh/auto-ppt-engine/smoke.yml?branch=main&label=CI)](https://github.com/lijunliu-gh/auto-ppt-engine/actions/workflows/smoke.yml)
-[![Tests](https://img.shields.io/badge/tests-409%20passed-brightgreen)](tests/)
-[![Coverage](https://img.shields.io/badge/coverage-84%25-green)](tests/)
-[![Python](https://img.shields.io/badge/python-3.10%2B-blue)](requirements.txt)
-[![Node](https://img.shields.io/badge/node-18%2B-green)](package.json)
-[![Docker](https://img.shields.io/badge/docker-ready-2496ED?logo=docker&logoColor=white)](Dockerfile)
-[![MCP](https://img.shields.io/badge/MCP-compatible-8A2BE2?logo=data:image/svg+xml;base64,PHN2ZyB4bWxucz0iaHR0cDovL3d3dy53My5vcmcvMjAwMC9zdmciIHZpZXdCb3g9IjAgMCAyNCAyNCIgZmlsbD0id2hpdGUiIHdpZHRoPSIxNiIgaGVpZ2h0PSIxNiI+PGNpcmNsZSBjeD0iMTIiIGN5PSIxMiIgcj0iMTAiLz48L3N2Zz4=)](mcp_server.py)
-[![PRs Welcome](https://img.shields.io/badge/PRs-welcome-brightgreen.svg)](CONTRIBUTING.md)
+<p align="center">
+  <a href="https://github.com/lijunliu-gh/auto-ppt-engine/tags"><img src="https://img.shields.io/github/v/tag/lijunliu-gh/auto-ppt-engine?label=release&sort=semver" alt="Release"></a>
+  <a href="LICENSE"><img src="https://img.shields.io/badge/license-MIT-blue.svg" alt="License"></a>
+  <a href="https://github.com/lijunliu-gh/auto-ppt-engine/actions/workflows/smoke.yml"><img src="https://img.shields.io/github/actions/workflow/status/lijunliu-gh/auto-ppt-engine/smoke.yml?branch=main&label=CI" alt="CI"></a>
+  <a href="tests/"><img src="https://img.shields.io/badge/tests-409%20passed-brightgreen" alt="Tests"></a>
+  <a href="tests/"><img src="https://img.shields.io/badge/coverage-84%25-green" alt="Coverage"></a>
+  <br>
+  <a href="requirements.txt"><img src="https://img.shields.io/badge/python-3.10%2B-blue" alt="Python"></a>
+  <a href="package.json"><img src="https://img.shields.io/badge/node-18%2B-green" alt="Node"></a>
+  <a href="Dockerfile"><img src="https://img.shields.io/badge/docker-ready-2496ED?logo=docker&logoColor=white" alt="Docker"></a>
+  <a href="mcp_server.py"><img src="https://img.shields.io/badge/MCP-compatible-8A2BE2" alt="MCP"></a>
+  <a href="CONTRIBUTING.md"><img src="https://img.shields.io/badge/PRs-welcome-brightgreen.svg" alt="PRs Welcome"></a>
+</p>
 
 Open-source PowerPoint generation engine — built to be called by AI agents.