Add GitHub Pages deploy status badge to README

Co-Authored-By: Claude <noreply@anthropic.com>

Author: k-l-lambda

README.md

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 # Paraff Live Editor
 
+[![Deploy to GitHub Pages](https://github.com/FindLab-org/paraff-live-editor/actions/workflows/deploy.yml/badge.svg)](https://github.com/FindLab-org/paraff-live-editor/actions/workflows/deploy.yml)
+
 A live editor for [Paraff](https://github.com/k-l-lambda/paraff) music notation with real-time MEI conversion and Verovio rendering.
 
 ## Features