ci: add build workflow

Adds a GitHub Actions workflow that runs npm run build on pushes to main and all pull requests, so changes that break the webpack build are caught in CI.

Co-Authored-By: Claude <noreply@anthropic.com>

Author: arbrandes

.github/workflows/ci.yml

@@ -0,0 +1,28 @@
+name: node_CI
+
+on:
+  push:
+    branches:
+    - main
+  pull_request:
+    branches:
+    - '**'
+
+jobs:
+  tests:
+    runs-on: ubuntu-latest
+
+    steps:
+    - name: Checkout
+      uses: actions/checkout@v4
+
+    - name: Setup Nodejs
+      uses: actions/setup-node@v4
+      with:
+        node-version-file: '.nvmrc'
+
+    - name: Install Dependencies
+      run: npm ci
+
+    - name: Build
+      run: npm run build