docs: missing_docs sweep — 0 warnings + deny gate + publish-prep decisions (HY-02, HY-04, HY-11)

- document every public-API item across 18 files (openapi_spec model,
  HttpAuthScheme/HttpServiceConfig, HttpClientBuildError + SharedHttpClient
  accessors, RetryAfterMiddleware, GatewayDispatch, gateway error
  mapping, CallRequest/SchemaQuery/SubscribeStream, HttpAdapter +
  ALPNs + builders, decoy/healthz/state, WsSessions/WsPumps,
  from_openapi/from_jsonschema/from_mcp/from_wss/to_mcp, lib.rs module
  docs)
- enforcement: #![deny(missing_docs)] at crate root — stronger than CI
  rustdocflags (every build incl. cfg(test), where rustdoc misses the
  test-support module docs)
- HY-10 (opportunistic): all 8 docs.rs/alkhttp placeholder ADR links +
  the one relative ../docs link converted to plain text; the 10
  pre-existing private/redundant intra-doc-link warnings fixed —
  RUSTDOCFLAGS="-D warnings" cargo doc is fully clean
- HY-11 decision: docs/ + tasks/ excluded from the published package
  (contributor-facing design/process material; ADR references degrade
  to plain text uniformly). cargo publish --dry-run: 38 files, ~889 KiB,
  zero docs/ or tasks/ entries
- HY-04 decision: keep + document — frame_channel0_chunk's unwrap is
  on serializing the acyclic EventEnvelope (unreachable failure);
  # Panics on it and the adjacent WsClient senders state the contract

Verified: cargo test (299 + 5 TLS), --all-features (370 + suites),
--no-default-features (299), clippy --all-targets -D warnings
(default + all-features), fmt --check, cargo doc -D warnings clean,
cargo publish --dry-run --allow-dirty clean.

Tasks: review-001-missing-docs-sweep (final pending task; 42/42)

src/websocket/byte_adapter.rs

@@ -38,8 +38,8 @@
 //! bytes drain (the mux's EOF sentinels ride the same queue).
 //!
 //! Shared with the `from_wss` consumer path (ADR-070): one
-//! implementation, both directions ([`WsFraming`] + the generic
-//! [`run_read_pump`] / [`run_write_pump`] instantiated once per socket
+//! implementation, both directions (`WsFraming` + the generic
+//! `run_read_pump` / `run_write_pump` instantiated once per socket
 //! flavor — WS-11/COV-03).
 
 use std::{
@@ -402,6 +402,8 @@ pub struct WsPumps {
 }
 
 impl WsPumps {
+    /// Abort both pump tasks (forced session teardown; the remote sees
+    /// an abrupt close, not a graceful one).
     pub fn abort(&self) {
         self.read_task.abort();
         self.write_task.abort();
@@ -454,8 +456,7 @@ impl WsFraming for AxumFraming {
 }
 
 /// Split a `WebSocket` into the byte stream + the pump tasks with the
-/// default idle-read timeout
-/// ([`DEFAULT_WS_IDLE_TIMEOUT`](crate::websocket::DEFAULT_WS_IDLE_TIMEOUT)).
+/// default idle-read timeout (`crate::websocket::DEFAULT_WS_IDLE_TIMEOUT`).
 /// See [`split_ws_to_bytes_idle`] for the configurable form.
 pub fn split_ws_to_bytes(socket: WebSocket) -> (WsByteStream, WsPumps) {
     split_ws_to_bytes_idle(socket, Some(DEFAULT_WS_IDLE_TIMEOUT))