test: add test infrastructure with CI workflow and image-gen unit tests

.github/workflows/test.yml

@@ -0,0 +1,21 @@
+name: Test
+
+on:
+  push:
+  pull_request:
+  workflow_dispatch:
+
+jobs:
+  node-tests:
+    runs-on: ubuntu-latest
+    steps:
+      - name: Checkout
+        uses: actions/checkout@v4
+
+      - name: Setup Node.js
+        uses: actions/setup-node@v4
+        with:
+          node-version: 22
+
+      - name: Run tests
+        run: npm test