feat: add logout method

proto/identity.proto

@@ -7,6 +7,7 @@ import "google/rpc/status.proto";
 service AuthService {
     rpc Login (LoginRequest) returns (LoginResponse);
     rpc Refresh (RefreshRequest) returns (RefreshResponse);
+    rpc Logout (LogoutRequest) returns (LogoutResponse);
     rpc Register (RegisterRequest) returns (RegisterResponse);
     rpc Verify2Fa (Verify2FaRequest) returns (Verify2FaResponse);
 }
@@ -47,6 +48,14 @@ message RefreshResponse {
   string refresh_token = 2;
 }
 
+message LogoutRequest {
+  string access_token = 1;
+}
+
+message LogoutResponse {
+  string message = 1;
+}
+
 message RegisterRequest {
   string username = 1;
   string password = 2;