fix(frontend): keep the MSW worker in step with the lockfile (#6222)

The tracked frontend/public/mockServiceWorker.js is generated by msw and pinned
at 2.14.7, while package-lock.json installs 2.15.0. msw rewrites the worker on
postinstall, so npm ci leaves the tree dirty on a clean checkout and every
contributor either commits an unrelated 30-line diff or discards it.

Regenerate the worker for the locked version and add a check that compares it
against the installed runtime, wired into make verify and CI so the pair cannot
drift again.

.github/workflows/ci.yml

@@ -182,6 +182,9 @@ 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