Add GitHub Actions release workflow

Builds binaries for darwin/linux on amd64/arm64 and creates
a GitHub release when a version tag is pushed.

Co-Authored-By: Claude Opus 4.5 <noreply@anthropic.com>

Author: yepzdk

.github/workflows/release.yaml

@@ -0,0 +1,34 @@
+name: Release
+
+on:
+  push:
+    tags:
+      - 'v*'
+
+permissions:
+  contents: write
+
+jobs:
+  release:
+    runs-on: ubuntu-latest
+    steps:
+      - name: Checkout
+        uses: actions/checkout@v4
+
+      - name: Set up Go
+        uses: actions/setup-go@v5
+        with:
+          go-version: '1.21'
+
+      - name: Build binaries
+        run: make build-all
+
+      - name: Create Release
+        uses: softprops/action-gh-release@v1
+        with:
+          files: |
+            dist/csm-darwin-amd64
+            dist/csm-darwin-arm64
+            dist/csm-linux-amd64
+            dist/csm-linux-arm64
+          generate_release_notes: true