ID-71 {71.26} — Platform-agents architecture (MOVED to reference/)

MOVED — Platform-agents architecture

The decided platform-agents architecture (authored here under ID-71 {71.26}, S458) now lives at reference/platform-agents-architecture.md — it is durable cross-task architecture (DR-042..DR-046, the per-client posture choice, the prove→pin→promote lifecycle, the two-leg observability plane, and the OQ-71.26-COST cost model), not id-71 spec provenance.

Promoted S491 (22/07/2026). The research input it supersedes stays in this spec dir: research-inputs/vercel-async-worker-architecture.md (provenance, unchanged).