* feat: add backend preview validation to ai evals Co-Authored-By: Claude Opus 4.5 <noreply@anthropic.com> * fix: refresh shared preview workspace assets Co-Authored-By: Claude Opus 4.5 <noreply@anthropic.com> * fix: harden shared backend preview validation Co-Authored-By: Claude Opus 4.5 <noreply@anthropic.com> --------- Co-authored-by: Claude Opus 4.5 <noreply@anthropic.com>