Applicants could bypass onboarding and land directly on the dashboard.
Added onboardingCompletedAt check + redirect to /onboarding in both
the applicant and observer layouts (jury/mentor already had this gate).
Also removed premature status ACTIVE on magic-link first login — now
only completeOnboarding sets ACTIVE.
Co-Authored-By: Claude Opus 4.6 <noreply@anthropic.com>