add AgentSessionStateDelta for state sync (#1393)

* add AgentSessionStateDelta for state sync

* generated protobuf

* update AgentSessionState

* generated protobuf

---------

Co-authored-by: github-actions <41898282+github-actions[bot]@users.noreply.github.com>

Author: longcw

livekit/livekit_agent.pb.go

@@ -187,12 +187,18 @@ message JobTermination {
   string job_id = 1;
 }
 
+message AgentSessionState {
+  uint64 version = 1;
+  bytes snapshot = 2;
+  bytes delta = 3;
+}
+
 message TextMessageRequest {
   string message_id = 1;
   string session_id = 2;
   string agent_name = 3;
   string metadata = 4;
-  bytes session_data = 5;
+  AgentSessionState session_state = 5;
   string text = 6;
 }
 
@@ -207,6 +213,6 @@ message PushTextRequest {
 message TextMessageResponse {
   // Indicate the request is completed
   string message_id = 1;
-  bytes session_data = 2;
+  AgentSessionState session_state = 2;
   string error = 3;
 }