Add release workflow for binaries and Docker image

Builds binaries for linux/macOS (x86_64 + aarch64), generates
checksums, creates a GitHub release, and pushes a multi-arch
Docker image to GHCR. Triggered on version tags (v*).

Co-Authored-By: Claude Opus 4.6 <noreply@anthropic.com>

Author: dittops

.github/workflows/release.yml

@@ -0,0 +1,133 @@
+name: Release
+
+on:
+  push:
+    tags:
+      - "v*"
+
+permissions:
+  contents: write
+  packages: write
+
+env:
+  CARGO_TERM_COLOR: always
+  REGISTRY: ghcr.io
+  IMAGE_NAME: ${{ github.repository }}
+
+jobs:
+  build:
+    strategy:
+      matrix:
+        include:
+          - target: x86_64-unknown-linux-gnu
+            os: ubuntu-latest
+            asset: taskgraph-linux-x86_64
+          - target: aarch64-unknown-linux-gnu
+            os: ubuntu-latest
+            asset: taskgraph-linux-aarch64
+          - target: x86_64-apple-darwin
+            os: macos-latest
+            asset: taskgraph-darwin-x86_64
+          - target: aarch64-apple-darwin
+            os: macos-latest
+            asset: taskgraph-darwin-aarch64
+
+    runs-on: ${{ matrix.os }}
+
+    steps:
+      - uses: actions/checkout@v4
+
+      - name: Install Rust toolchain
+        run: |
+          rustup target add ${{ matrix.target }}
+
+      - name: Install cross-compilation tools
+        if: matrix.target == 'aarch64-unknown-linux-gnu'
+        run: |
+          sudo apt-get update
+          sudo apt-get install -y gcc-aarch64-linux-gnu
+
+      - name: Build
+        env:
+          CARGO_TARGET_AARCH64_UNKNOWN_LINUX_GNU_LINKER: aarch64-linux-gnu-gcc
+        run: cargo build --release --target ${{ matrix.target }}
+
+      - name: Package binary
+        run: |
+          cp target/${{ matrix.target }}/release/taskgraph ${{ matrix.asset }}
+          chmod +x ${{ matrix.asset }}
+
+      - name: Upload artifact
+        uses: actions/upload-artifact@v4
+        with:
+          name: ${{ matrix.asset }}
+          path: ${{ matrix.asset }}
+
+  release:
+    needs: build
+    runs-on: ubuntu-latest
+
+    steps:
+      - uses: actions/checkout@v4
+
+      - name: Download all artifacts
+        uses: actions/download-artifact@v4
+        with:
+          path: artifacts
+
+      - name: Prepare release assets
+        run: |
+          mkdir release
+          for dir in artifacts/*/; do
+            cp "$dir"* release/
+          done
+          cd release
+          sha256sum taskgraph-* > checksums.txt
+          cat checksums.txt
+
+      - name: Create GitHub release
+        uses: softprops/action-gh-release@v2
+        with:
+          generate_release_notes: true
+          files: release/*
+
+  docker:
+    needs: release
+    runs-on: ubuntu-latest
+
+    steps:
+      - uses: actions/checkout@v4
+
+      - name: Set up Docker Buildx
+        uses: docker/setup-buildx-action@v3
+
+      - name: Set up QEMU
+        uses: docker/setup-qemu-action@v3
+
+      - name: Log in to GHCR
+        uses: docker/login-action@v3
+        with:
+          registry: ${{ env.REGISTRY }}
+          username: ${{ github.actor }}
+          password: ${{ secrets.GITHUB_TOKEN }}
+
+      - name: Extract metadata
+        id: meta
+        uses: docker/metadata-action@v5
+        with:
+          images: ${{ env.REGISTRY }}/${{ env.IMAGE_NAME }}
+          tags: |
+            type=semver,pattern={{version}}
+            type=semver,pattern={{major}}.{{minor}}
+            type=raw,value=latest
+
+      - name: Build and push
+        uses: docker/build-push-action@v6
+        with:
+          context: .
+          platforms: linux/amd64,linux/arm64
+          push: true
+          tags: ${{ steps.meta.outputs.tags }}
+          labels: ${{ steps.meta.outputs.labels }}
+          cache-from: type=gha
+          cache-to: type=gha,mode=max