fix(frontend): remove unused MSW browser worker (#6859)

The frontend uses MSW only through its Node test interceptor, but the unused browser worker requires synchronization after dependency updates and currently breaks make verify.

Remove the unused asset, worker-directory configuration, and freshness checks while preserving Node MSW tests and the separate PWA worker. Update tooling descriptions to match.

Fixes #6858

.github/workflows/ci.yml

@@ -201,9 +201,6 @@ jobs:
       - name: Install
         run: npm ci
         working-directory: frontend
-      - name: Verify generated MSW worker is current
-        run: git diff --exit-code -- public/mockServiceWorker.js package-lock.json
-        working-directory: frontend
       - name: Lint
         run: npm run lint
         working-directory: frontend