feat: server foundation (phase 1 core) — state, auth, healthz/decoy, gateway dispatch, HttpAdapter

Tasks completed: server-core-types, server-auth, server-healthz-decoy,
gateway-dispatch, server-adapter (5 of 17).

- src/server/state.rs: DecoyConfig + RouterState (alkcall type paths,
  6-endpoint reserved-path docs)
- src/server/auth.rs: bearer middleware + ResolvedIdentity extractor
  (10 tests: missing/malformed/basic/failed-resolution matrix)
- src/server/healthz.rs + decoy.rs: raw healthz; nginx-style 404,
  static site (path-traversal guarded), redirect decoys
- src/gateway/dispatch.rs: GatewayDispatch invoke/invoke_streaming
  (internal:false, forwarded_for:None, bounded deadline) +
  src/gateway/error.rs: CallError→HTTP status mapping (HTTP_<status>
  passthrough, retryable→Retry-After)
- src/server/adapter.rs: HttpAdapter ProtocolHandler — accept_bi →
  BiStream → TokioIo → hyper auto builder (h2 CONNECT enabled);
  integration tests over DuplexStream (request/response cycle, healthz,
  decoy 404)

Verified: cargo test (46 lib tests), clippy -D warnings, fmt,
test --all-features.

tasks/server/auth.md

@@ -1,7 +1,7 @@
 ---
 id: server-auth
 name: Bearer auth middleware and identity extraction
-status: pending
+status: completed
 depends_on: [server-core-types]
 scope: narrow
 risk: low
@@ -23,10 +23,10 @@ static identity provider.
 
 ## Acceptance Criteria
 
-- [ ] Middleware ports with tests (missing header, malformed, valid token, unknown token)
-- [ ] `set_identity` observability path documented for the WS route's use
-- [ ] No env-var reads anywhere (no-env-vars invariant)
-- [ ] `cargo test` passes
+- [x] Middleware ports with tests (missing header, malformed, valid token, unknown token)
+- [x] `set_identity` observability path documented for the WS route's use
+- [x] No env-var reads anywhere (no-env-vars invariant)
+- [x] `cargo test` passes
 
 ## References
 
@@ -39,4 +39,9 @@ static identity provider.
 
 ## Summary
 
-> Agent fills on completion.
+Ported `src/server/auth.rs`: `bearer_auth_middleware`,
+`extract_bearer_identity`, `ResolvedIdentity` extractor — resolution
+semantics preserved (no header/malformed/failed resolution → None;
+routes decide 401 vs anonymous). 10 unit tests covering the matrix.
+alkcall type paths. The WS route's `set_identity` observability is
+documented in the module doc of adapter.rs.