init ci

.github/workflows/main.yml

@@ -0,0 +1,19 @@
+name: Test
+on:
+  push:
+    branches:
+      - main
+jobs:
+  typecheck:
+    runs-on: ubuntu-latest
+    steps:
+      - name: Checkout code
+        uses: actions/checkout@v2
+      - name: Set up Node.js
+        uses: actions/setup-node@v2
+        with:
+          node-version: 20
+      - name: Install dependencies
+        run: npm ci
+      - name: Run typecheck
+        run: npm run typecheck