fix(radar): show activation before opt-in

[diegosouzapw]

Summary

• keep RADAR_ENABLED availability separate from the independent Radar sync opt-in
• render the activation screen when /api/radar/settings returns 200 { optIn: false }
• preserve the true flag-off 404 behavior when the endpoint returns 404

Root cause

The dashboard overloaded optIn === false to mean both “feature flag off” and “feature available but owner has not opted in”. A fresh installation therefore called notFound() immediately after the settings API correctly returned 200 { optIn: false }.

TDD / live reproduction

• RED: tests/unit/radar-optin-page.test.tsx reproduced settings 200 + optIn false -> notFound() (2 calls)
• GREEN: the same response renders the activation screen and never calls notFound()
• regression: a real settings 404 still calls notFound()
• live pre-fix Playwright on VPS .15: /api/radar/settings returned 200, followed by the rendered dashboard 404

Validation

• npx vitest run tests/unit/radar-optin-page.test.tsx — 2/2
• focused Node Radar tests — green
• npm run typecheck:core — green
• scoped ESLint + Prettier — green
• git diff --check — green