fix: discover empty-preview Rescue children

[vitry]

Summary

• replace incomplete global Codex child discovery with exact parent relationship queries so restored empty-preview children remain visible
• fail closed on Codex versions that silently ignore or do not support the exact-parent API, while preserving host-only occupancy without follow-up authority
• add the production collision regression, update bilingual guidance, and refresh the verified marketplace snapshot

Verification

• npm run check
• real installed Codex 0.149 replay for parent 01a022d7-aa12-7112-abe0-78036571802e, including a spaced/slashed originator override
• independent Standards and Spec reviews: approved with zero findings

Safety

• no global-list fallback, collision retry, private Codex storage read, or ZCode Rescue usage