Add GitHub Actions workflow and remove Travis CI

Co-authored-by: DRSDavidSoft <4673812+DRSDavidSoft@users.noreply.github.com>

Author: Copilot

.github/workflows/ci.yml

@@ -0,0 +1,38 @@
+name: CI
+
+on:
+  push:
+    branches: [ master ]
+  pull_request:
+    branches: [ master ]
+
+jobs:
+  build-and-test:
+    runs-on: ubuntu-latest
+    
+    steps:
+    - name: Checkout code
+      uses: actions/checkout@v4
+      
+    - name: Set up Ruby
+      uses: ruby/setup-ruby@v1
+      with:
+        ruby-version: '3.2'
+        bundler-cache: true
+        
+    - name: Install dependencies
+      run: bundle install
+      
+    - name: Build Jekyll site
+      run: bundle exec jekyll build
+      
+    - name: Run HTMLProofer
+      run: bundle exec htmlproofer ./_site --disable-external
+      
+    - name: Upload site artifacts
+      uses: actions/upload-artifact@v4
+      if: success()
+      with:
+        name: site
+        path: _site/
+        retention-days: 7

.travis.yml

@@ -1,4 +1,4 @@
 # cmderdev.github.io
 The cmder.net page.
 
-[![Build Status](https://travis-ci.org/cmderdev/cmderdev.github.io.svg?branch=master)](https://travis-ci.org/cmderdev/cmderdev.github.io)
+[![CI](https://github.com/cmderdev/cmderdev.github.io/actions/workflows/ci.yml/badge.svg)](https://github.com/cmderdev/cmderdev.github.io/actions/workflows/ci.yml)