Force npm ci in test-frontend to fix stale cache missing transforms

The cached node_modules was missing react-scripts babel config after
package-lock.json changed (remark-gfm addition). Tests failed with
'Cannot use import statement outside a module' and JSX parse errors.
Always run npm ci to ensure fresh dependencies match the lockfile.

.gitlab-ci.yml

@@ -118,7 +118,7 @@ test-frontend:
         - node_modules/
       policy: pull
   script:
-    - cd frontend && (test -d node_modules || npm ci) && cd .. && (test -d node_modules || npm ci) && cd frontend && CI=true npx react-scripts test --watchAll=false --ci
+    - cd frontend && npm ci && cd .. && (test -d node_modules || npm ci) && cd frontend && CI=true npx react-scripts test --watchAll=false --ci
   timeout: 5 minutes
   needs:
     - install-frontend