chore: Add CI workflow checks.

.github/workflows/ecko-checks.yml

@@ -0,0 +1,31 @@
+name: Ecko Checks
+
+on:
+  pull_request:
+
+jobs:
+  check:
+    name: Checks and tests
+    runs-on: ubuntu-latest
+
+    steps:
+      - name: Checkout code
+        uses: actions/checkout@v4
+
+      - name: Setup Node.js
+        uses: actions/setup-node@v4
+        with:
+          node-version: 22
+          cache: npm
+
+      - name: Install packages
+        run: npm ci
+
+      - name: Lint
+        run: npm run lint
+
+      - name: Typecheck
+        run: npm run typecheck
+
+      - name: Test
+        run: npm run test