Add GitHub Actions workflow for PR validation with build and test jobs

.github/workflows/build.yml

@@ -0,0 +1,57 @@
+name: PR Validation
+
+on:
+  pull_request:
+    branches:
+      - main
+
+env:
+  CARGO_TERM_COLOR: always
+
+jobs:
+  build-and-test:
+    runs-on: ${{ matrix.platform.os }}
+
+    strategy:
+      fail-fast: false
+
+      matrix:
+        platform:
+          - os: ubuntu-latest
+            target: x86_64-unknown-linux-gnu
+            command: cargo
+
+          - os: ubuntu-latest
+            target: aarch64-unknown-linux-gnu
+            command: cross
+
+          - os: windows-latest
+            target: x86_64-pc-windows-msvc
+            command: cargo
+
+    steps:
+      - name: Checkout code
+        uses: actions/checkout@v4
+
+      - name: Cache Cargo and cross
+        uses: actions/cache@v4
+        with:
+          path: |
+            ~/.cargo/registry
+            ~/.cargo/git
+            ~/.cargo/bin
+          key: ${{ matrix.platform.target }}-cargo-${{ hashFiles('**/Cargo.lock') }}
+          restore-keys: ${{ matrix.platform.target }}-cargo
+
+      - name: Install cross
+        if: matrix.platform.command == 'cross'
+        run: |
+          if ! command -v cross &>/dev/null; then
+            cargo install cross
+          fi
+
+      - name: Build
+        run: ${{ matrix.platform.command }} build --target ${{ matrix.platform.target }}
+
+      - name: Test
+        run: ${{ matrix.platform.command }} test --target ${{ matrix.platform.target }}