ci: typecheck and build the demo

.github/dependabot.yml

@@ -7,6 +7,14 @@ updates:
     groups:
       dev-dependencies:
         dependency-type: development
+  - package-ecosystem: npm
+    directory: /demo
+    schedule:
+      interval: weekly
+    groups:
+      demo-dependencies:
+        patterns:
+          - '*'
   - package-ecosystem: github-actions
     directory: /
     schedule:

.github/workflows/ci.yml

@@ -26,6 +26,22 @@ jobs:
           token: ${{ secrets.CODECOV_TOKEN }}
           fail_ci_if_error: false
 
+  demo:
+    name: Demo typecheck & build
+    runs-on: ubuntu-latest
+    steps:
+      - uses: actions/checkout@v4
+      - uses: actions/setup-node@v4
+        with:
+          node-version: 22
+          cache: npm
+      # The demo aliases the package to ../src, so the root install has to
+      # exist for its dependencies to resolve.
+      - run: npm ci
+      - run: npm --prefix demo ci
+      - run: npm --prefix demo run typecheck
+      - run: npm --prefix demo run build
+
   test:
     name: Test (Node ${{ matrix.node }}, React ${{ matrix.react }})
     runs-on: ubuntu-latest

demo/package.json

@@ -5,6 +5,7 @@
   "type": "module",
   "scripts": {
     "dev": "vite",
+    "typecheck": "tsc --noEmit",
     "build": "vite build",
     "preview": "vite preview"
   },