ci: add GitHub Actions validation pipeline

.github/workflows/ci.yml

@@ -0,0 +1,46 @@
+name: CI
+
+on:
+  pull_request:
+    branches:
+      - main
+  push:
+    branches:
+      - main
+
+permissions:
+  contents: read
+
+concurrency:
+  group: ci-${{ github.workflow }}-${{ github.ref }}
+  cancel-in-progress: true
+
+jobs:
+  validate:
+    name: Validate Python
+    runs-on: ubuntu-latest
+
+    steps:
+      - name: Checkout repository
+        uses: actions/checkout@v4
+
+      - name: Set up Python
+        uses: actions/setup-python@v5
+        with:
+          python-version: "3.11"
+          cache: pip
+          cache-dependency-path: |
+            requirements.txt
+            requirements-dev.txt
+
+      - name: Install system dependencies
+        run: sudo apt-get update && sudo apt-get install -y ffmpeg
+
+      - name: Install dependencies
+        run: make install-dev
+
+      - name: Run lint smoke checks
+        run: make lint
+
+      - name: Run test suite
+        run: make test