fix: add CI badge to README for build status visibility

Author: milisp

README.md

@@ -9,6 +9,7 @@
 [![Issues](https://img.shields.io/github/issues/milisp/codexia)](https://github.com/milisp/codexia/issues)
 [![PRs Welcome](https://img.shields.io/badge/PRs-welcome-brightgreen.svg)](#-contributing)
 [![License: MIT](https://img.shields.io/badge/License-MIT-yellow.svg)](LICENSE)
+[![CI](https://github.com/milisp/codexia/actions/workflows/ci.yml/badge.svg)](https://github.com/milisp/codexia/actions/workflows/ci.yml)
 
 
 A modern, multi-session GUI application for the [Codex CLI](https://github.com/openai/codex) built with Tauri v2, React, and TypeScript.