Add CI workflow for PRs and Dependabot auto-merge

.github/workflows/ci.yml

@@ -0,0 +1,29 @@
+name: CI
+
+on:
+  pull_request:
+
+jobs:
+  test:
+    runs-on: ubuntu-latest
+    steps:
+      - name: Checkout
+        uses: actions/checkout@v4
+
+      - name: Setup Node.js
+        uses: actions/setup-node@v4
+        with:
+          node-version: 22
+          cache: npm
+
+      - name: Install dependencies
+        run: npm ci
+
+      - name: Run tests
+        run: npm test
+
+      - name: Type check
+        run: npm run check
+
+      - name: Build site
+        run: npm run build

.github/workflows/dependabot-automerge.yml

@@ -0,0 +1,19 @@
+name: Dependabot Auto-Merge
+
+on:
+  pull_request:
+
+permissions:
+  contents: write
+  pull-requests: write
+
+jobs:
+  automerge:
+    runs-on: ubuntu-latest
+    if: github.event.pull_request.user.login == 'dependabot[bot]'
+    steps:
+      - name: Enable auto-merge
+        run: gh pr merge --auto --squash "$PR_URL"
+        env:
+          PR_URL: ${{ github.event.pull_request.html_url }}
+          GH_TOKEN: ${{ secrets.GITHUB_TOKEN }}