Add CI workflow

.github/workflows/ci.yml

@@ -0,0 +1,37 @@
+name: CI
+
+on:
+  pull_request:
+  push:
+    branches: [main]
+
+jobs:
+  quality:
+    name: python sanity checks
+    runs-on: ubuntu-latest
+
+    steps:
+      - name: Checkout
+        uses: actions/checkout@v4
+
+      - name: Setup Python
+        uses: actions/setup-python@v5
+        with:
+          python-version: "3.12"
+          cache: pip
+
+      - name: Install dependencies
+        run: |
+          python -m pip install --upgrade pip
+          python -m pip install -r requirements.txt
+
+      - name: Compile Python files
+        run: python -m compileall .
+
+      - name: Run tests if present
+        shell: bash
+        run: |
+          if [ -d tests ]; then
+            python -m pip install pytest
+            pytest -q
+          fi