Add PR build

.github/workflows/build.yml

@@ -0,0 +1,37 @@
+name: Build HTML content from source
+
+on:
+  pull_request:
+    branches:
+      - '*'
+
+  # Allows you to run this workflow manually from the Actions tab
+  workflow_dispatch:
+
+concurrency:
+  group: "pages"
+  cancel-in-progress: false
+
+jobs:
+  build:
+    runs-on: ubuntu-latest
+    steps:
+      - name: Checkout
+        uses: actions/checkout@v4
+      - name: Setup Ruby
+        uses: ruby/setup-ruby@v1
+        with:
+          ruby-version: '3.3'
+      - name: Install dependencies
+        run: bundle install
+      - name: Build with Middleman
+        run: |
+          mkdir __build
+          BUILD_OUTPUT="__build" middleman build
+      - name: Generate HTML Preview
+        id: html_preview
+        uses: pavi2410/html-preview-action@v2
+        with:
+          html_file: '__build/index.html'
+      - name: Access preview
+        run: echo "${{steps.html_preview.outputs.url}}"

config.rb

@@ -74,7 +74,7 @@ def configure_blog(blog)
   ignored
 end
 
-set :build_dir,  'docs'
+set :build_dir,  ENV.fetch('BUILD_OUTPUT', 'docs')
 set :css_dir,    'stylesheets'
 set :js_dir,     'javascripts'
 set :images_dir, 'images'