ci: revert composite build to reusable workflow

.github/workflows/_build.yml

@@ -0,0 +1,30 @@
+on:
+  workflow_call:
+    outputs:
+      artifact_id:
+        value: ${{ jobs.build.outputs.artifact_id }}
+
+jobs:
+  build:
+    outputs:
+      artifact_id: ${{ steps.upload-artifact.outputs.artifact_id }}
+    runs-on: ubuntu-latest
+    steps:
+      - uses: actions/checkout@v4
+      - uses: ruby/setup-ruby@v1
+        with:
+          ruby-version: "3.3"
+          bundler-cache: true # runs 'bundle install' and caches installed gems automatically
+          cache-version: 0 # Increment this number if you need to re-download cached gems
+      - name: Setup Pages
+        id: pages
+        uses: actions/configure-pages@v5
+      - name: Build with Jekyll
+        # Outputs to the './_site' directory by default
+        run: bundle exec jekyll build --baseurl "${{ steps.pages.outputs.base_path }}"
+        env:
+          JEKYLL_ENV: production
+      - name: Upload artifact
+        # Automatically uploads an artifact from the './_site' directory by default
+        uses: actions/upload-pages-artifact@v3
+        id: upload-artifact

.github/workflows/deploy.yml

@@ -21,8 +21,7 @@ jobs:
   build:
     runs-on: ubuntu-latest
     steps:
-      - uses: actions/checkout@v4
-      - uses: ./.github/workflows/jekyll-build.yml
+      - uses: ./.github/workflows/_build.yml
 
   # Deployment job
   deploy: