Simplify hook runtime state

Remove the unused pending-hook layer and dead protocol trait wrappers, and resolve active hooks through a direct active-only flow with peer-side indexing instead of scan-based recovery.

src/protocol/tree/endpoint/receive.rs

@@ -65,7 +65,6 @@ impl ProtocolEndpoint {
                     peer_path: header.src_path.clone(),
                     procedure_id: message.procedure_id.clone(),
                     dst_leaf: header.dst_leaf.clone(),
-                    peer_finished: false,
                 })
                 .is_err()
         {