refactor(frontend): reset and enforce frontend architecture

[BrainerVirus]

Summary

• reset the frontend to the new app, domains, features, and shared architecture with direct imports and no public or barrel paths
• split oversized settings, worklog, play, onboarding, tray, schedule, GitLab auth, store, and shared UI modules into smaller colocated units with focused tests
• enforce the architecture with zero remaining line-limit exceptions and document the change in the changelog

Test Plan

• npm run lint
• npm run test
• npm run build