Merge feat/http-bearer-auth-middleware: Shared Bearer auth middleware

Implements src/server/auth.rs: bearer_auth_middleware (from_fn_with_state over
Arc<dyn IdentityProvider>, stashes Option<Identity> in request extensions),
extract_bearer_identity (Bearer-only: no/malformed/Basic/unresolvable → None,
not an error), ResolvedIdentity axum extractor. Wired into HttpAdapter router
via route_layer around gateway/openapi/mcp routes, excluding /healthz. 11 tests.

# Conflicts:
#	crates/alknet-http/Cargo.toml
#	crates/alknet-http/src/server/adapter.rs
#	crates/alknet-http/src/server/mod.rs

crates/alknet-http/Cargo.toml

@@ -46,4 +46,4 @@ rmcp = { version = "1.8", optional = true, default-features = false, features =
 
 [dev-dependencies]
 http-body-util = "0.1"
-tower = { version = "0.5", features = ["util"] }
+tower = { version = "0.5", features = ["util"] }