perf: parallelize binary builds in release workflow

Split the monolithic binary build step into a matrix job with 3 parallel
runners (server, wfctl, lsp-server). Each builds its platform variants
concurrently, uploads artifacts, and the release job collects them all.

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

Author: intel352

.github/workflows/release.yml

@@ -134,16 +134,31 @@ jobs:
         build-args: |
           NPM_TOKEN=${{ secrets.GITHUB_TOKEN }}
 
-  release:
-    name: Create GitHub Release
+  build-binaries:
+    name: Build ${{ matrix.name }} binaries
     runs-on: ubuntu-latest
-    needs: [test, build-ui]
+    needs: test
+    strategy:
+      fail-fast: false
+      matrix:
+        include:
+          - name: server
+            cmd: ./cmd/server
+            prefix: workflow
+            platforms: linux/amd64 linux/arm64 darwin/amd64 darwin/arm64 windows/amd64
+          - name: wfctl
+            cmd: ./cmd/wfctl
+            prefix: wfctl
+            platforms: linux/amd64 linux/arm64 darwin/amd64 darwin/arm64 windows/amd64
+          - name: lsp-server
+            cmd: ./cmd/workflow-lsp-server
+            prefix: workflow-lsp-server
+            # Windows LSP build skipped: tliron/kutil v0.3.11 has a termenv API mismatch on Windows.
+            platforms: linux/amd64 linux/arm64 darwin/amd64 darwin/arm64
 
     steps:
     - name: Check out code
       uses: actions/checkout@v4
-      with:
-        fetch-depth: 0
 
     - name: Set up Go
       uses: actions/setup-go@v5
@@ -172,24 +187,41 @@ jobs:
         VERSION=${GITHUB_REF#refs/tags/}
         LDFLAGS="-s -w -X main.version=${VERSION}"
 
-        GOOS=linux   GOARCH=amd64 go build -ldflags="${LDFLAGS}" -o dist/workflow-linux-amd64    ./cmd/server
-        GOOS=linux   GOARCH=arm64 go build -ldflags="${LDFLAGS}" -o dist/workflow-linux-arm64    ./cmd/server
-        GOOS=darwin  GOARCH=amd64 go build -ldflags="${LDFLAGS}" -o dist/workflow-darwin-amd64   ./cmd/server
-        GOOS=darwin  GOARCH=arm64 go build -ldflags="${LDFLAGS}" -o dist/workflow-darwin-arm64   ./cmd/server
-        GOOS=windows GOARCH=amd64 go build -ldflags="${LDFLAGS}" -o dist/workflow-windows-amd64.exe ./cmd/server
-
-        GOOS=linux   GOARCH=amd64 go build -ldflags="${LDFLAGS}" -o dist/wfctl-linux-amd64    ./cmd/wfctl
-        GOOS=linux   GOARCH=arm64 go build -ldflags="${LDFLAGS}" -o dist/wfctl-linux-arm64    ./cmd/wfctl
-        GOOS=darwin  GOARCH=amd64 go build -ldflags="${LDFLAGS}" -o dist/wfctl-darwin-amd64   ./cmd/wfctl
-        GOOS=darwin  GOARCH=arm64 go build -ldflags="${LDFLAGS}" -o dist/wfctl-darwin-arm64   ./cmd/wfctl
-        GOOS=windows GOARCH=amd64 go build -ldflags="${LDFLAGS}" -o dist/wfctl-windows-amd64.exe ./cmd/wfctl
-
-        GOOS=linux   GOARCH=amd64 go build -ldflags="${LDFLAGS}" -o dist/workflow-lsp-server-linux-amd64    ./cmd/workflow-lsp-server
-        GOOS=linux   GOARCH=arm64 go build -ldflags="${LDFLAGS}" -o dist/workflow-lsp-server-linux-arm64    ./cmd/workflow-lsp-server
-        GOOS=darwin  GOARCH=amd64 go build -ldflags="${LDFLAGS}" -o dist/workflow-lsp-server-darwin-amd64   ./cmd/workflow-lsp-server
-        GOOS=darwin  GOARCH=arm64 go build -ldflags="${LDFLAGS}" -o dist/workflow-lsp-server-darwin-arm64   ./cmd/workflow-lsp-server
-        # Windows LSP build skipped: tliron/kutil v0.3.11 has a termenv API mismatch on Windows.
-        # Tracked upstream. Server/wfctl Windows builds are unaffected.
+        for platform in ${{ matrix.platforms }}; do
+          GOOS="${platform%/*}"
+          GOARCH="${platform#*/}"
+          output="dist/${{ matrix.prefix }}-${GOOS}-${GOARCH}"
+          if [ "${GOOS}" = "windows" ]; then
+            output="${output}.exe"
+          fi
+          echo "Building ${output}..."
+          GOOS="${GOOS}" GOARCH="${GOARCH}" go build -ldflags="${LDFLAGS}" -o "${output}" ${{ matrix.cmd }}
+        done
+
+    - name: Upload binaries
+      uses: actions/upload-artifact@v4
+      with:
+        name: binaries-${{ matrix.name }}
+        path: dist/*
+        retention-days: 1
+
+  release:
+    name: Create GitHub Release
+    runs-on: ubuntu-latest
+    needs: [build-binaries, build-ui]
+
+    steps:
+    - name: Check out code
+      uses: actions/checkout@v4
+      with:
+        fetch-depth: 0
+
+    - name: Download all binary artifacts
+      uses: actions/download-artifact@v4
+      with:
+        pattern: binaries-*
+        path: dist
+        merge-multiple: true
 
     - name: Download admin UI artifact
       uses: actions/download-artifact@v4