ci: gate on typecheck

.github/workflows/ci.yml

@@ -42,3 +42,22 @@ jobs:
         run: npm run test:smoke
         env:
           NODE_OPTIONS: --max-old-space-size=12288
+
+  typecheck:
+    runs-on: ubuntu-latest
+    timeout-minutes: 15
+    steps:
+      - uses: actions/checkout@v4
+
+      - uses: actions/setup-node@v4
+        with:
+          node-version: '22'
+          cache: 'npm'
+
+      - name: Install dependencies
+        run: npm ci
+
+      - name: Typecheck
+        run: npm run typecheck
+        env:
+          NODE_OPTIONS: --max-old-space-size=12288