Add automated quality checks

.github/workflows/ci.yml

@@ -0,0 +1,44 @@
+name: Frontend quality checks
+
+on:
+  pull_request:
+    branches: [main]
+  push:
+    branches: [main]
+
+permissions:
+  contents: read
+
+jobs:
+  frontend:
+    name: Frontend lint, tests, and build
+    runs-on: ubuntu-latest
+    timeout-minutes: 15
+    defaults:
+      run:
+        working-directory: frontend
+    steps:
+      - name: Check out repository
+        uses: actions/checkout@v4
+
+      - name: Set up Node.js
+        uses: actions/setup-node@v4
+        with:
+          node-version: 22
+          cache: npm
+          cache-dependency-path: frontend/package-lock.json
+
+      - name: Install frontend dependencies
+        run: npm ci
+
+      - name: Lint frontend
+        run: npm run lint
+
+      - name: Run frontend tests
+        run: npm test
+
+      - name: Build frontend
+        env:
+          NEXT_PUBLIC_SUPABASE_URL: https://ci-placeholder.supabase.co
+          NEXT_PUBLIC_SUPABASE_ANON_KEY: ci-placeholder-anon-key
+        run: npm run build