fix(up-03): PeerCompositeEnv::peer_operations override — list-peers sees peer-announced ops

Surfaced by alkhttp review 006 (UP-03): services/list-peers showed
every peer with an empty operations array. PeerCompositeEnv overrode
peer_ids only, so peer_operations fell to the trait default
(Vec::new()) and the ADR-022 amendment's "announced op is discoverable
via services/list-peers" promise never resolved on the wire. ADR-030
prescribed the fix but it had never been ported into alkcall. The
existing list-peers unit tests passed because they mock
peer_operations with hand-rolled envs.

Implements ADR-030 as specified:
- OperationEnv gains list_operation_names (default Vec::new(),
  back-compat for all existing implementors)
- OverlayOperationEnv overrides it with its overlay's registered names
- PeerCompositeEnv::peer_operations delegates to the peer overlay's
  list_operation_names; PeerCompositeEnv::list_operation_names
  aggregates session + connections + base (mirrors its contains())
- LocalOperationEnv enumerates its registry; ChannelsSessionEnv
  delegates to base

Gate: announced_op_is_discoverable_via_services_list_peers in
src/registry/op_register.rs — announces an op through op/register,
then asserts both the direct peer_operations probe and the
services/list-peers wire shape attribute the announced op to the peer,
over the exact compose_root_env shape (PeerCompositeEnv + attached
connection overlay). Verified load-bearing: reverting the
peer_operations override fails the gate.

ADR-030 status Proposed -> Accepted with the UP-03 provenance note.

Verification: 590 default / 607 all-features tests, clippy
(all-targets, all-features, wasm32) clean, fmt clean, doc clean,
semver-checks 196 pass against v0.3.0 (defaulted trait method is
non-breaking).

docs/architecture/decisions/030-peer-composite-env-peer-operations.md

@@ -2,7 +2,15 @@
 
 ## Status
 
-Proposed
+Accepted (implemented 2026-09-04 — surfaced as UP-03 in alkhttp's
+review 006 `docs/…/006-alkcall-0.3.0-consequence-review.md`: the
+`op/register` amendment's "announced op is discoverable via
+`services/list-peers`" promise did not resolve on the wire because
+this override had never been ported into alkcall; the gate is
+`announced_op_is_discoverable_via_services_list_peers` in
+`src/registry/op_register.rs`. The `services/list-peers` unit tests
+did not catch it because they mock `peer_operations` with hand-rolled
+envs.)
 
 ## Context