Playwright coverage for the dashboard First Agent wizard #41

Summary

Dashboard has a multi-step First Agent wizard (#wizard-progress) with no browser test. Login/overview is covered; onboarding wizard is not.

Context

• dashboard/index.html (wizard progress)
• tests/browser/test_critical_paths.py (test_dashboard_login_and_overview)

Acceptance criteria

• Register/login via UI (cookies, no JWT paste)
• Open onboarding wizard and complete at least the first steps through sample call with mocks
• Assert progress marks and overview/session evidence
• make test-browser green