Add coverage badge to README, fix Pages deploy to preserve demo.gif

- Add shields.io coverage badge using endpoint from GitHub Pages
- Deploy job now checks out gh-pages first so demo.gif is preserved
  alongside badge.json

Author: Fivell

.github/workflows/ci.yml

@@ -68,19 +68,23 @@ jobs:
       url: ${{ steps.deployment.outputs.page_url }}
 
     steps:
+      - uses: actions/checkout@v4
+        with:
+          ref: gh-pages
+
       - name: Download coverage badge
         uses: actions/download-artifact@v4
         with:
           name: coverage-badge
-          path: coverage
+          path: .
 
       - name: Setup Pages
         uses: actions/configure-pages@v5
 
       - name: Upload Pages artifact
         uses: actions/upload-pages-artifact@v3
         with:
-          path: coverage
+          path: .
 
       - name: Deploy to GitHub Pages
         id: deployment

README.md

@@ -1,6 +1,7 @@
 [![Gem Version](https://badge.fury.io/rb/active_admin_sidebar.svg)](https://badge.fury.io/rb/active_admin_sidebar)
 [![NPM Version](https://badge.fury.io/js/@activeadmin-plugins%2Factive_admin_sidebar.svg)](https://badge.fury.io/js/@activeadmin-plugins%2Factive_admin_sidebar)
 ![npm](https://img.shields.io/npm/dm/@activeadmin-plugins/active_admin_sidebar)
+![Coverage](https://img.shields.io/endpoint?url=https://activeadmin-plugins.github.io/active_admin_sidebar/badge.json)
 
 # ActiveAdmin Sidebar