ci: add GitHub Actions workflow for cargo test, fmt, clippy, and go test

.github/workflows/test.yml

@@ -0,0 +1,75 @@
+name: test
+
+on:
+  push:
+    branches:
+      - main
+      - master
+      - "claude/**"
+  pull_request:
+  workflow_dispatch:
+
+concurrency:
+  group: ${{ github.workflow }}-${{ github.ref }}
+  cancel-in-progress: true
+
+env:
+  CARGO_TERM_COLOR: always
+  RUST_BACKTRACE: 1
+
+jobs:
+  rust-test:
+    name: cargo test (workspace)
+    runs-on: ubuntu-latest
+    timeout-minutes: 30
+    steps:
+      - uses: actions/checkout@v4
+      - uses: dtolnay/rust-toolchain@stable
+      - uses: Swatinem/rust-cache@v2
+        with:
+          shared-key: workspace
+      - run: cargo test --workspace --all-features --no-fail-fast
+
+  rust-fmt:
+    name: cargo fmt --check
+    runs-on: ubuntu-latest
+    timeout-minutes: 5
+    steps:
+      - uses: actions/checkout@v4
+      - uses: dtolnay/rust-toolchain@stable
+        with:
+          components: rustfmt
+      - run: cargo fmt --all -- --check
+
+  rust-clippy:
+    name: cargo clippy
+    runs-on: ubuntu-latest
+    timeout-minutes: 30
+    # Clippy has never been enforced on this repo; surface findings without
+    # blocking other jobs until the codebase is brought into compliance.
+    continue-on-error: true
+    steps:
+      - uses: actions/checkout@v4
+      - uses: dtolnay/rust-toolchain@stable
+        with:
+          components: clippy
+      - uses: Swatinem/rust-cache@v2
+        with:
+          shared-key: workspace
+      - run: cargo clippy --workspace --all-targets --all-features -- -D warnings
+
+  go-test:
+    name: go test (poly-verified-go)
+    runs-on: ubuntu-latest
+    timeout-minutes: 15
+    defaults:
+      run:
+        working-directory: poly-verified-go
+    steps:
+      - uses: actions/checkout@v4
+      - uses: actions/setup-go@v5
+        with:
+          go-version-file: poly-verified-go/go.mod
+          cache: false
+      - run: go vet ./...
+      - run: go test ./... -race -count=1