Tracking: net-http Tier-3 architectural re-cuts (supersede ADRs)

[NotAProfDev]

Clean-slate re-cuts from docs/superpowers/plans/2026-07-06-net-http-deep-review.md §5 that CONTRADICT approved ADR-0030/0031/0034 — each needs a new/superseding ADR before implementation:

• Typed local-vs-venue error (replace flat HttpError/ErrorKind conflation; root of C1's class)
• Typed per-request directive envelope (replace http::Extensions typemap)
• Split RateLimit into separate rate + concurrency layers
• Buffering as a layer above the leaf (not leaf-owned)