Add GitHub Actions workflow to build Lambda deployment package

.github/workflows/build-lambda-package.yml

@@ -0,0 +1,40 @@
+name: Build Lambda Package
+
+on:
+  push:
+    branches:
+      - main
+  pull_request:
+
+jobs:
+  build:
+    runs-on: ubuntu-latest
+
+    steps:
+      - name: Checkout repository
+        uses: actions/checkout@v4
+
+      - name: Set up Go
+        uses: actions/setup-go@v5
+        with:
+          go-version: '1.21'
+
+      - name: Run tests
+        run: go test ./...
+
+      - name: Build Lambda binary
+        env:
+          GOOS: linux
+          GOARCH: amd64
+          CGO_ENABLED: 0
+        run: go build -tags lambda -o bootstrap
+
+      - name: Package Lambda artifact
+        run: zip function.zip bootstrap
+
+      - name: Upload artifact
+        uses: actions/upload-artifact@v4
+        with:
+          name: lambda-function
+          path: function.zip
+          if-no-files-found: error