ci: separate E2E tests into dedicated job

- Create separate 'e2e' job that runs after 'check' job
- E2E tests run in parallel after check passes
- Each job has its own environment and build step
- Clearer separation between unit tests and E2E tests in CI output

Author: geelen

.github/workflows/check.yml

@@ -27,5 +27,21 @@ jobs:
       - name: Build
         run: pnpm build
 
+  e2e:
+    runs-on: ubuntu-latest
+    needs: check
+
+    steps:
+      - name: Checkout code
+        uses: actions/checkout@v4
+
+      - name: Setup pnpm & install
+        uses: wyvox/action-setup-pnpm@v3
+        with:
+          node-version: 22
+
+      - name: Build
+        run: pnpm build
+
       - name: Run E2E tests
         run: cd test && pnpm install && pnpm test