Add CI/CD release pipeline for cross-platform builds

Introduces GitHub Actions workflow triggered on version tags (v*)
that runs tests, builds release binaries for 4 targets
(aarch64/x86_64 macOS + Linux), and publishes a GitHub Release.

Co-Authored-By: Claude Opus 4.6 <noreply@anthropic.com>

Author: stephenleo

.github/workflows/release.yml

@@ -0,0 +1,75 @@
+name: Release
+
+on:
+  push:
+    tags:
+      - 'v*'
+  workflow_dispatch:
+
+jobs:
+  test:
+    name: Test (${{ matrix.os }})
+    runs-on: ${{ matrix.os }}
+    strategy:
+      matrix:
+        os: [ubuntu-latest, macos-latest]
+    steps:
+      - uses: actions/checkout@v4
+      - name: Install Rust stable
+        uses: dtolnay/rust-toolchain@stable
+        with:
+          components: rustfmt, clippy
+      - uses: Swatinem/rust-cache@v2
+      - name: Check formatting
+        run: cargo fmt --check
+      - name: Clippy
+        run: cargo clippy -- -D warnings
+      - name: Test
+        run: cargo test
+
+  build:
+    name: Build (${{ matrix.target }})
+    needs: test
+    runs-on: ${{ matrix.runner }}
+    strategy:
+      matrix:
+        include:
+          - target: aarch64-apple-darwin
+            runner: macos-latest
+          - target: x86_64-apple-darwin
+            runner: macos-13
+          - target: x86_64-unknown-linux-gnu
+            runner: ubuntu-latest
+          - target: aarch64-unknown-linux-gnu
+            runner: ubuntu-24.04-arm
+    steps:
+      - uses: actions/checkout@v4
+      - name: Install Rust stable
+        uses: dtolnay/rust-toolchain@stable
+        with:
+          targets: ${{ matrix.target }}
+      - uses: Swatinem/rust-cache@v2
+      - name: Build release binary
+        run: cargo build --release --target ${{ matrix.target }}
+      - name: Rename binary
+        run: cp target/${{ matrix.target }}/release/cship cship-${{ matrix.target }}
+      - name: Validate binary
+        run: |
+          file cship-${{ matrix.target }}
+          test -s cship-${{ matrix.target }} || { echo "ERROR: binary is empty"; exit 1; }
+      - uses: actions/upload-artifact@v4
+        with:
+          name: cship-${{ matrix.target }}
+          path: cship-${{ matrix.target }}
+
+  release:
+    name: Publish GitHub Release
+    needs: build
+    runs-on: ubuntu-latest
+    permissions:
+      contents: write
+    steps:
+      - uses: actions/download-artifact@v4
+      - uses: softprops/action-gh-release@v2
+        with:
+          files: cship-*/cship-*