chore(deps): consume alkcall 0.8.0

- bump alkcall 0.7 -> 0.8 (gateway feature unchanged). No code change
  forced: alkcall 0.8.0 is additive on the call-plane JSON and the
  registry seams (review 008's remediation — the establisher reply
  projection, flavor-form open-op ids in discovery, the in-tree
  ChannelRelay + hub-leg install template) and none of the new
  surfaces are constructed in this crate: no Establishment reply
  fields (the WS ferry passes Option<OpenEstablisher> through
  unchanged), no marked specs imported through from_call (the from_wss
  filter excludes the protocol-session ops), no ChannelRelay /
  HubLegImports / HubLegTemplate consumption (hub-leg assembly stays
  at the assembly layer)
- one ride-through on this crate's discovery surface: a deployment's
  with_ws_openable_alpns open-op specs with non-standard names now
  serve an explicit channel_open_alpn string through services/list +
  services/schema (alkcall 0.8.0 U-1, ADR-047 amendment 3) so hubs
  relaying via from_call reconstruct the marker; standard-shape names
  stay byte-stable

Verification: cargo test 456 pass (default) / 589 (all-features),
clippy --all-targets -D warnings clean (default + all-features),
fmt --check clean, doc --no-deps clean

Cargo.toml

@@ -1,6 +1,6 @@
 [package]
 name = "alkhttp"
-version = "0.4.1"
+version = "0.5.0"
 edition = "2021"
 rust-version = "1.88"
 license = "MIT OR Apache-2.0"
@@ -42,7 +42,7 @@ h2 = ["server", "dep:hyper", "hyper-util/http2", "hyper/http2"]
 http1 = ["server", "dep:hyper", "hyper-util/http1", "hyper/http1"]
 
 [dependencies]
-alkcall = { version = "0.7", features = ["gateway"] }
+alkcall = { version = "0.8", features = ["gateway"] }
 arc-swap = { version = "1", optional = true }
 axum = { version = "0.8", optional = true, features = ["ws"] }
 bytes = "1"