add CI workflow

Author: cmatheson

.github/workflows/ci.yml

@@ -0,0 +1,26 @@
+name: CI
+
+on:
+  push:
+    branches:
+      - "main"
+  pull_request: {}
+
+jobs:
+  checks:
+    name: Pre-merge Checks
+    runs-on: ubuntu-latest
+    steps:
+      - uses: actions/checkout@v4
+      - uses: actions/setup-node@v4
+        with:
+          node-version: 20
+
+      - name: Setup
+        run: npm ci
+
+      - name: Check formatting
+        run: npm run format:check
+
+      - name: Test build
+        run: npm run build

package.json

@@ -13,6 +13,8 @@
   ],
   "scripts": {
     "build": "tsup",
+    "format": "prettier --write .",
+    "format:check": "prettier --check .",
     "test": "echo \"Error: no test specified\" && exit 1"
   },
   "repository": {