feat(acp): route session/setTitle to the new schema types

Wires the SetSessionTitleRequest / SetSessionTitleResponse types into
the agent-side JSON-RPC dispatch tables.

Companion to agentclientprotocol/agent-client-protocol#1199,
which adds the schema definitions for session/setTitle. This PR is the
Rust SDK half of the round trip: once the schema crate ships a release
with the new types, ACP-backed agents can implement Agent::set_session_title
and have it dispatched here.

Author: daniel-agentee

src/agent-client-protocol/src/schema/client_to_agent/requests.rs

@@ -4,6 +4,7 @@ use crate::schema::{
     LoadSessionRequest, LoadSessionResponse, NewSessionRequest, NewSessionResponse, PromptRequest,
     PromptResponse, ResumeSessionRequest, ResumeSessionResponse, SetSessionConfigOptionRequest,
     SetSessionConfigOptionResponse, SetSessionModeRequest, SetSessionModeResponse,
+    SetSessionTitleRequest, SetSessionTitleResponse,
 };
 #[cfg(feature = "unstable_session_fork")]
 use crate::schema::{ForkSessionRequest, ForkSessionResponse};
@@ -30,6 +31,11 @@ impl_jsonrpc_request!(
     SetSessionConfigOptionResponse,
     "session/set_config_option"
 );
+impl_jsonrpc_request!(
+    SetSessionTitleRequest,
+    SetSessionTitleResponse,
+    "session/setTitle"
+);
 
 #[cfg(feature = "unstable_session_model")]
 impl_jsonrpc_request!(

src/agent-client-protocol/src/schema/enum_impls.rs

@@ -21,6 +21,7 @@ impl_jsonrpc_request_enum!(ClientRequest {
     CloseSessionRequest => "session/close",
     SetSessionModeRequest => "session/set_mode",
     SetSessionConfigOptionRequest => "session/set_config_option",
+    SetSessionTitleRequest => "session/setTitle",
     PromptRequest => "session/prompt",
     #[cfg(feature = "unstable_session_model")]
     SetSessionModelRequest => "session/set_model",