ci: add GitHub Actions release workflow for multi-platform build, package, and publish

.github/workflows/release.yml

@@ -0,0 +1,81 @@
+name: release
+
+on:
+  push:
+    tags:
+      - 'v*'
+  workflow_dispatch:
+    inputs:
+      tag:
+        description: 'Release tag (e.g. v1.2.3). If empty, uses current ref name.'
+        required: false
+        type: string
+
+permissions:
+  contents: write
+
+jobs:
+  build-and-package:
+    runs-on: ubuntu-latest
+    steps:
+      - name: Checkout
+        uses: actions/checkout@v4
+
+      - name: Setup Go
+        uses: actions/setup-go@v5
+        with:
+          go-version-file: go.mod
+          cache: true
+
+      - name: Install packaging tools
+        run: |
+          sudo apt-get update
+          sudo apt-get install -y zip
+
+      - name: Build all platforms
+        run: |
+          make build-all BUILD_TARGETS="linux/amd64 linux/arm64 linux/riscv64 darwin/amd64 darwin/arm64 windows/amd64 windows/arm64"
+
+      - name: Package artifacts
+        run: make package-all BUILD_TARGETS="linux/amd64 linux/arm64 linux/riscv64 darwin/amd64 darwin/arm64 windows/amd64 windows/arm64"
+
+      - name: Upload artifacts
+        uses: actions/upload-artifact@v4
+        with:
+          name: release-artifacts
+          path: |
+            build/*.tar.gz
+            build/*.zip
+            build/checksums.txt
+          if-no-files-found: error
+
+  publish-release:
+    needs: build-and-package
+    runs-on: ubuntu-latest
+    if: startsWith(github.ref, 'refs/tags/') || github.event_name == 'workflow_dispatch'
+    steps:
+      - name: Download artifacts
+        uses: actions/download-artifact@v4
+        with:
+          name: release-artifacts
+          path: build
+
+      - name: Resolve tag
+        id: tag
+        run: |
+          if [ "${{ github.event_name }}" = "workflow_dispatch" ] && [ -n "${{ inputs.tag }}" ]; then
+            echo "name=${{ inputs.tag }}" >> "$GITHUB_OUTPUT"
+          else
+            echo "name=${GITHUB_REF_NAME}" >> "$GITHUB_OUTPUT"
+          fi
+
+      - name: Create GitHub Release
+        uses: softprops/action-gh-release@v2
+        with:
+          tag_name: ${{ steps.tag.outputs.name }}
+          name: ${{ steps.tag.outputs.name }}
+          generate_release_notes: true
+          files: |
+            build/*.tar.gz
+            build/*.zip
+            build/checksums.txt