ci: add GitHub Actions workflow to run tests on PRs and main

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

Author: wassimk

.github/workflows/ci.yml

@@ -0,0 +1,16 @@
+name: ci
+
+on:
+  push:
+    branches: [main]
+  pull_request:
+    branches: [main]
+
+jobs:
+  test:
+    runs-on: macos-latest
+    steps:
+      - uses: actions/checkout@v4
+
+      - name: Run tests
+        run: cargo test