docs(turn-loop): fix stale AgentRequest/ManagerRequest wire-type names

Verified against hive-agent/src/main.rs and hive-core-agent-sock/src/lib.rs:
there is no AgentRequest/AgentResponse or ManagerRequest/ManagerResponse
alias anywhere in the tree — hive-agent uses hive_core_agent_sock's
unified Request/Response enum directly.

docs/turn-loop/README.md

@@ -67,8 +67,8 @@ agents) runs:
 
 Two sibling crates, both role-agnostic (there is one role: agent —
 the privilege boundary lives server-side at the broker socket
-(`/run/hive/mcp.sock`), which refuses `ManagerRequest` calls regardless
-of who sends them):
+(`/run/hive/mcp.sock`), which refuses privileged `Request` variants
+regardless of who sends them):
 
 - `hive-agent` — long-running harness loop (the inbox poll +
   claude-pump + ack/requeue cycle described above).
@@ -79,10 +79,11 @@ of who sends them):
   transport — no per-turn stdio child (eliminates the re-registration
   race).
 
-`hive-agent`'s wire types (`AgentRequest` / `AgentResponse`, aliased as
-`ManagerRequest` / `ManagerResponse`) and its turn loop are factored
-through a small `Surface` trait with one zero-sized impl, so the loop
-itself has no per-role branches. See `hive-agent/src/main.rs`'s module
+`hive-agent`'s wire types (`hive_core_agent_sock::{Request, Response}` —
+one unified enum shared by the agent and manager sockets) and its turn
+loop are factored through a small `Surface` trait with one zero-sized
+impl, so the loop itself has no per-role branches. See
+`hive-agent/src/main.rs`'s module
 doc for the trait shape.
 
 ### Boot wiring