fix(ci): link CLI binary for E2E tests

Some E2E tests invoke `deepl` directly via execSync rather than
through the node helper. npm link makes the binary available on PATH.

Co-Authored-By: Claude Opus 4.6 <noreply@anthropic.com>

Author: sjsyrek

.github/workflows/ci.yml

@@ -27,4 +27,6 @@ jobs:
       - run: npm run lint
       - run: npm run type-check
       - run: npm run build
+      - name: Link CLI for E2E tests
+        run: npm link
       - run: npm test