ci: add Go verification workflow

.github/workflows/ci.yml

@@ -0,0 +1,51 @@
+name: CI
+
+on:
+  pull_request:
+  push:
+    branches:
+      - main
+  workflow_dispatch:
+
+permissions:
+  contents: read
+
+concurrency:
+  group: ${{ github.workflow }}-${{ github.ref }}
+  cancel-in-progress: true
+
+jobs:
+  verify:
+    name: Go verification
+    runs-on: ubuntu-latest
+    timeout-minutes: 20
+    steps:
+      - uses: actions/checkout@v4
+      - uses: actions/setup-go@v5
+        with:
+          go-version-file: go.mod
+          cache: true
+      - name: Check formatting
+        run: |
+          unformatted="$(gofmt -l $(git ls-files -- '*.go'))"
+          if [ -n "$unformatted" ]; then
+            printf 'gofmt required:\n%s\n' "$unformatted"
+            exit 1
+          fi
+      - name: Vet
+        run: go vet ./...
+      - name: Test
+        run: go test -count=1 ./...
+
+  race:
+    name: Race detection
+    runs-on: ubuntu-latest
+    timeout-minutes: 20
+    steps:
+      - uses: actions/checkout@v4
+      - uses: actions/setup-go@v5
+        with:
+          go-version-file: go.mod
+          cache: true
+      - name: Test concurrent TEE and API paths
+        run: go test -race -count=1 ./cmd/gaiko2 ./internal/api ./internal/tee