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/Cargo.toml

@@ -0,0 +1,40 @@
+[package]
+name = "alknet-http"
+version.workspace = true
+edition.workspace = true
+license.workspace = true
+description = "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"
+repository.workspace = true
+
+[lib]
+name = "alknet_http"
+
+[features]
+default = ["h2", "http1"]
+mcp = ["dep:rmcp"]
+h2 = ["dep:hyper"]
+http1 = ["dep:hyper"]
+
+[dependencies]
+alknet-core = { path = "../alknet-core" }
+alknet-call = { path = "../alknet-call" }
+axum = { version = "0.8", features = ["ws"] }
+hyper = { version = "1", optional = true, features = ["server", "http1", "http2"] }
+reqwest = { version = "0.13", default-features = false, features = ["json", "stream"] }
+reqwest-middleware = "0.5"
+reqwest-retry = "0.9"
+tokio = { version = "1", features = ["full"] }
+serde = { version = "1", features = ["derive"] }
+serde_json = "1"
+async-trait = "0.1"
+tracing = "0.1"
+thiserror = "2"
+uuid = { version = "1", features = ["v4"] }
+futures = "0.3"
+openapiv3 = "2"
+rmcp = { version = "1.8", optional = true, default-features = false, features = [
+    "client",
+    "server",
+    "transport-streamable-http-client-reqwest",
+    "transport-streamable-http-server",
+] }

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