Add GitHub Actions workflow for code verification

This workflow defines jobs for verifying Go code, including building, vetting, and testing with race detection.

.github/workflows/verify.yml

@@ -0,0 +1,31 @@
+name: verify
+
+on:
+  push:
+  pull_request:
+
+permissions:
+  contents: read
+
+jobs:
+  verify:
+    runs-on: [self-hosted, windows]
+    steps:
+      - uses: actions/checkout@v4
+      - run: go build ./...
+      - run: go vet ./...
+      - run: go test ./...
+
+  race:
+    runs-on: [self-hosted, windows]
+    steps:
+      - uses: actions/checkout@v4
+      # Density-based world tests are intentionally exhaustive and race adds
+      # substantial overhead; keep the package timeout above the normal 10m.
+      - run: go test -race -timeout 20m ./...
+
+  parity:
+    runs-on: [self-hosted, windows]
+    steps:
+      - uses: actions/checkout@v4
+      - run: go test ./internal/world -run TestVanillaBlockParity -count=1 -v