ci: add github action

Author: simonsmith

.github/workflows/ci.yml

@@ -0,0 +1,38 @@
+name: CI
+
+on:
+  push:
+    branches: [master]
+  pull_request:
+    branches: [master]
+
+jobs:
+  test:
+    runs-on: ubuntu-latest
+
+    steps:
+      - name: Checkout code
+        uses: actions/checkout@v4
+
+      - name: Setup Node.js
+        uses: actions/setup-node@v4
+        with:
+          node-version: '22'
+
+      - name: Enable Corepack
+        run: corepack enable
+
+      - name: Set Yarn version
+        run: corepack prepare [email protected] --activate
+
+      - name: Install dependencies
+        run: yarn install --immutable
+
+      - name: Check TypeScript types
+        run: yarn typecheck
+
+      - name: Check Prettier formatting
+        run: yarn chk
+
+      - name: Run tests
+        run: yarn test