feat(http): initialize alknet-http crate with module skeleton

Add crates/alknet-http with Cargo.toml, src/lib.rs, and the five
subsystem modules (server, gateway, client, adapters, websocket) per
ADR-039 (server + client host colocated). The mcp feature gate pulls in
rmcp with streamable HTTP transport features only (ADR-037 — no stdio);
h3/WebTransport is absent (deferred per ADR-044). alknet-core and
alknet-call use workspace path deps. The crate is added to the workspace
members list.

crates/alknet-http/src/adapters/mod.rs

@@ -0,0 +1,11 @@
+//! HTTP-backed call-protocol adapters: `from_openapi`, `to_openapi`,
+//! `from_mcp`, `to_mcp`.
+//!
+//! `from_openapi`/`from_mcp` are the no-env-vars credential injection point
+//! (ADR-014); `to_openapi`/`to_mcp` are projections of the local registry
+//! (ADR-017). `from_mcp`/`to_mcp` are feature-gated behind `mcp`
+//! (streamable HTTP only — ADR-037). See
+//! `docs/architecture/crates/http/http-adapters.md` and
+//! `docs/architecture/crates/http/http-mcp.md`.
+
+// TODO: implement

crates/alknet-http/src/client/mod.rs

@@ -0,0 +1,6 @@
+//! Shared HTTP client (`ClientWithMiddleware`): reqwest + retry middleware
+//! stack, used by `from_openapi`/`from_mcp` forwarding handlers.
+//!
+//! See `docs/architecture/crates/http/http-adapters.md` and OQ-40.
+
+// TODO: implement

crates/alknet-http/src/gateway/mod.rs

@@ -0,0 +1,7 @@
+//! Gateway: shared dispatch spine (`GatewayDispatch`) and error mapping.
+//!
+//! The 5 fixed gateway endpoints (`/search`, `/schema`, `/call`, `/batch`,
+//! `/subscribe`) are the sole HTTP invoke path (ADR-042/047). See
+//! `docs/architecture/crates/http/http-server.md`.
+
+// TODO: implement

crates/alknet-http/src/lib.rs

@@ -0,0 +1,13 @@
+//! alknet-http: HTTP interface for alknet — serves HTTP/1.1 + HTTP/2 on
+//! standard ALPNs (with WebSocket upgrade for browser bidirectional access)
+//! and hosts the HTTP-backed call-protocol adapters.
+//!
+//! Two roles in one crate (ADR-039): HTTP server (HttpAdapter, a
+//! ProtocolHandler for h2/http1.1 + WS upgrade) and HTTP client host
+//! (from_openapi/from_mcp forwarding, to_openapi/to_mcp projections).
+
+pub mod adapters;
+pub mod client;
+pub mod gateway;
+pub mod server;
+pub mod websocket;

crates/alknet-http/src/server/mod.rs

@@ -0,0 +1,9 @@
+//! HTTP server: `HttpAdapter`, axum-over-QUIC, gateway routes, `/healthz`,
+//! decoy, and custom routes.
+//!
+//! Implements `alknet_core::types::ProtocolHandler` for the standard HTTP
+//! ALPNs (`h2`, `http/1.1`) with WebSocket upgrade for browser
+//! bidirectional access (ADR-044). See
+//! `docs/architecture/crates/http/http-server.md`.
+
+// TODO: implement

crates/alknet-http/src/websocket/mod.rs

@@ -0,0 +1,7 @@
+//! WebSocket upgrade handler, framing, and dispatch handoff.
+//!
+//! WebSocket is the browser bidirectional path (ADR-044) and carries the
+//! native `EventEnvelope` call-protocol session, not the gateway shape
+//! (ADR-048). See `docs/architecture/crates/http/websocket.md`.
+
+// TODO: implement