Documents all 4 RECON-INFRA requirement IDs as complete, summarizes
decisions (per-source limiters, default-allow robots, SHA256 dedup,
UA pool of 10), lists handoff contract for Phases 10-16.
- Stealth UA pool (10 browsers) + RandomUserAgent/StealthHeaders
- Stable cross-source Dedup keyed by sha256(provider|masked|source)
- Mark RECON-INFRA-06 complete