setup: add tests and github workflow (#7)

Adds tests, lints, prettier checks, etc.

.eslint.config.js

@@ -0,0 +1,9 @@
+// @ts-check
+
+import eslint from "@eslint/js";
+import tseslint from "typescript-eslint";
+
+export default tseslint.config(
+  eslint.configs.recommended,
+  ...tseslint.configs.recommended,
+);

.github/workflows/ci.yml

@@ -0,0 +1,45 @@
+name: CI
+
+on:
+  pull_request:
+
+jobs:
+  lint:
+    name: Format
+    runs-on: ubuntu-latest
+
+    steps:
+      - uses: actions/checkout@v4
+
+      - name: Set up Node
+        uses: actions/setup-node@v4
+
+      - run: npm ci
+
+      - name: Prettier
+        run: |
+          npx prettier --check .
+
+      - name: eslint
+        run: |
+          npx eslint
+
+  build:
+    name: Build and test
+    runs-on: ubuntu-latest
+
+    steps:
+      - uses: actions/checkout@v4
+
+      - name: Set up Node
+        uses: actions/setup-node@v4
+
+      - run: npm ci
+
+      - name: Build
+        run: |
+          npm run build
+
+      - name: Test
+        run: |
+          npm run test