Add release workflow for cross-platform binary builds

Triggered on version tags (v*). Builds standalone binaries via PyInstaller
on Linux/macOS/Windows runners, wraps the Linux binary in a .deb via fpm,
and attaches all artifacts to a GitHub release.

https://claude.ai/code/session_01MqEqGhP1guGx5VuFsLaws2

.github/workflows/release.yml

@@ -0,0 +1,116 @@
+name: Release
+
+on:
+  push:
+    tags:
+      - "v*"
+
+permissions:
+  contents: write
+
+jobs:
+  build:
+    name: Build — ${{ matrix.label }}
+    runs-on: ${{ matrix.os }}
+    strategy:
+      fail-fast: false
+      matrix:
+        include:
+          - os: ubuntu-latest
+            label: Linux amd64
+            binary_name: mdcms
+            artifact_name: mdcms-linux-amd64
+            make_deb: true
+
+          - os: macos-latest
+            label: macOS arm64
+            binary_name: mdcms
+            artifact_name: mdcms-macos-arm64
+            make_deb: false
+
+          - os: windows-latest
+            label: Windows amd64
+            binary_name: mdcms.exe
+            artifact_name: mdcms-windows-amd64
+            make_deb: false
+
+    steps:
+      - uses: actions/checkout@v4
+
+      - uses: actions/setup-python@v5
+        with:
+          python-version: "3.12"
+
+      - name: Install dependencies
+        run: pip install pyinstaller click pyyaml
+
+      - name: Build binary
+        run: pyinstaller --onefile --name mdcms mdcms.py
+
+      - name: Rename binary (non-Windows)
+        if: matrix.os != 'windows-latest'
+        run: mv dist/mdcms dist/${{ matrix.artifact_name }}
+
+      - name: Rename binary (Windows)
+        if: matrix.os == 'windows-latest'
+        run: mv dist/mdcms.exe dist/${{ matrix.artifact_name }}.exe
+
+      - name: Build .deb (Linux only)
+        if: matrix.make_deb
+        run: |
+          VERSION=${GITHUB_REF_NAME#v}
+          gem install fpm --no-document
+          fpm \
+            -s dir -t deb \
+            -n mdcms \
+            -v "$VERSION" \
+            --description "MD-CMS companion CLI — manage and build MD-CMS sites" \
+            --url "https://github.com/kbenestad/mdcms" \
+            --maintainer "Kristian Benestad" \
+            --license "Apache-2.0" \
+            --architecture amd64 \
+            --category utils \
+            dist/mdcms-linux-amd64=/usr/local/bin/mdcms
+
+      - name: Upload binary artifact
+        uses: actions/upload-artifact@v4
+        with:
+          name: ${{ matrix.artifact_name }}
+          path: |
+            dist/${{ matrix.artifact_name }}
+            dist/${{ matrix.artifact_name }}.exe
+          if-no-files-found: ignore
+
+      - name: Upload .deb artifact
+        if: matrix.make_deb
+        uses: actions/upload-artifact@v4
+        with:
+          name: deb-package
+          path: "*.deb"
+
+  release:
+    name: Create GitHub Release
+    needs: build
+    runs-on: ubuntu-latest
+    steps:
+      - name: Download all artifacts
+        uses: actions/download-artifact@v4
+        with:
+          path: artifacts
+          merge-multiple: false
+
+      - name: List artifacts
+        run: find artifacts -type f
+
+      - name: Create release
+        uses: softprops/action-gh-release@v2
+        with:
+          name: mdcms ${{ github.ref_name }}
+          draft: false
+          prerelease: ${{ contains(github.ref_name, '-') }}
+          generate_release_notes: true
+          files: |
+            artifacts/mdcms-linux-amd64/mdcms-linux-amd64
+            artifacts/mdcms-macos-arm64/mdcms-macos-arm64
+            artifacts/mdcms-windows-amd64/mdcms-windows-amd64.exe
+            artifacts/deb-package/*.deb