fix: update docker-compose V1 syntax to V2 and add release PDF workflow

Replace remaining docker-compose command references with docker compose (V2).
Add GitHub Actions workflow to auto-generate PDF via mdpress on release.

.github/workflows/release-pdf.yml

@@ -0,0 +1,48 @@
+name: Build PDF on Release
+
+on:
+  release:
+    types: [published]
+  workflow_dispatch:
+
+permissions:
+  contents: write
+
+jobs:
+  build-pdf:
+    name: Generate PDF
+    runs-on: ubuntu-latest
+    steps:
+      - name: Checkout code
+        uses: actions/checkout@v4
+
+      - name: Install Chromium
+        run: |
+          sudo apt-get update
+          sudo apt-get install -y chromium-browser
+
+      - name: Install mdpress (latest)
+        run: |
+          LATEST_TAG=$(curl -fsSL https://api.github.com/repos/yeasy/mdpress/releases/latest | jq -r .tag_name)
+          VERSION="${LATEST_TAG#v}"
+          echo "Installing mdpress $VERSION"
+          curl -fsSL "https://github.com/yeasy/mdPress/releases/download/$LATEST_TAG/mdpress_${VERSION}_linux_amd64.tar.gz" -o mdpress.tar.gz
+          tar xzf mdpress.tar.gz
+          sudo mv mdpress /usr/local/bin/
+          mdpress --version
+
+      - name: Build PDF
+        run: mdpress build --format pdf --output docker_practice.pdf
+
+      - name: Upload PDF to Release
+        if: github.event_name == 'release'
+        uses: softprops/action-gh-release@v2
+        with:
+          files: docker_practice.pdf
+
+      - name: Upload PDF as artifact
+        if: github.event_name == 'workflow_dispatch'
+        uses: actions/upload-artifact@v4
+        with:
+          name: docker_practice-pdf
+          path: docker_practice.pdf