test: isolate GenericWorkbench settings state

[SuperPauly]

Summary

• apply localStorage and fetch cleanup to both GenericWorkbench test suites
• exercise reduced-validation re-preflight using an active schema
• preserve production behavior while removing cross-test state leakage

Verification

• npm run lint
• npm run typecheck
• npm run test:run
• npm run test:scripts
• npm run build
• npm run test:e2e

Security

• CodeQL was not run: repository default setup is not configured and no local CodeQL CLI is installed.