TX-N7B — Add concrete HTTP client package

[coenttb]

Summary

Completes the source-only concrete HTTP client on the public checked-out bounded-pool owner.

Related to #1.

Current source head

HTTP Client 710ecba54f5e2e315faad4e563a9aea40b30497d is the current pre-launch source head.

Per the 2026-08-11 principal ruling, every Package.swift dependency follows branch: "main" until tag launch on 14 September. Exact SHAs belong only in the frozen graph receipt.

Requirement map:

• swift-http-body: revision: "0f670ceb05701fbaaea9141342ba295d20ca4ee8" → branch: "main"
• swift-pool-primitives: revision: "b7c710c945b7c8467b4521c3a2d5b00539275593" → branch: "main"
• swift-io: revision: "271da4dee53063379776337a6a3b1be21751babb" → branch: "main"
• swift-sockets: revision: "74a57fa388e07e09f985fee89075577993c75c5b" → branch: "main"
• swift-tls: revision: "e27e99f5c841170593dde7b0396e9090a7515f62" → branch: "main"

The corrective successor changes only Package.swift. All N5 source, products, targets, and settings remain unchanged; Package.resolved remains untouched.

Pool and exchange ownership

The private swift-pools / Pool.Lease facade and now-unused Either dependency are removed. HTTP.Client stores Pool.Bounded<Connection> directly and checks out the deliberately non-Sendable handle by sending. Connection, its nominal operation, and its result are move-only. One attempt consumes one move-only request and returns a sending move-only response. Every checked-out handle is consumed by resolve: reusable and invalid success carry the response through terminal pool cleanup, while failure carries the typed client error through invalidation. Concurrent shutdown therefore cannot erase an already-produced response.

The connection operation is not @Sendable: it belongs to the exclusively checked-out move-only connection and is never independently shared. Retry policy remains @Sendable because it is reusable immutable policy over copyable request-head/error state.

Retry disposition

Only .none is replayable: HTTP Client retains the copyable request head and reconstructs one fresh body-free request for each eligible idempotent attempt. .bytes and .stream are consumed by exactly one attempt because HTTP Body exposes no producer-owned replay factory. No request is copied, retained after consumption, captured by a reusable closure, or hidden in a box.

Architecture constraints

TLS.Peer.Identity remains the sole DNS-query/hostname relation. No private pool facade, compatibility lease, SPI, trait, public with* API, unchecked conformance, request box, or local stream wrapper was added.

UNVERIFIED — full source-only moratorium: no build, test, resolve, update, clean, run, compose, verify, typecheck, lint, compiler probe, CI read/watch/poll, or Package.resolved operation was performed.

[coenttb]

Sockets exact-pin successor

Head ddb8569d42868c7be43c138981ad1e75328e8140 changes only Package.swift, pinning Sockets 74a57fa388e07e09f985fee89075577993c75c5b exactly. Static producer/client inspection found no HTTP Client dependency on the changed Listener/Accepted/listener-capability lifecycle, so no source adaptation is owned here. The direct Pool.Bounded checked-out-handle work from 5e298615b24fa7a61d9fe96c800be19a563eba78 is preserved unchanged.

UNVERIFIED - full source-only moratorium remained in force; Package.resolved was untouched.