Stop gating env-builder.js behind cookie auth to eliminate iframe 401

Merge branch 'edit' into codex/investigate-environment-builder-issues

Remove quick guide and fix right-panel scrolling

Hide env-builder toolbar hint on narrow screens

Polish env-builder UX with quick guide and required selector

Use GATEWAY_PORT in seeded config and readiness comment

Enhance Space Privacy Detection, Proxy Defaults, and Environment Builder UX

Upload env-builder.html