Add AgentError disconnect reason, docs, remove unused file

include/livekit/room_event_types.h

@@ -78,22 +78,40 @@ enum class EncryptionState {
 ///
 /// These values mirror the server-side DisconnectReason enum.
 enum class DisconnectReason {
+  /// Unknown or unspecified disconnect reason.
   Unknown = 0,
+  /// The client initiated the disconnect.
   ClientInitiated,
+  /// Another participant with the same identity has joined the room.
   DuplicateIdentity,
+  /// The server instance is shutting down.
   ServerShutdown,
+  /// The participant was removed from the room by the server.
   ParticipantRemoved,
+  /// The room was deleted by the server.
   RoomDeleted,
+  /// The client is attempting to resume a session, but server is not aware of it.
   StateMismatch,
+  /// Client was unable to connect fully.
   JoinFailure,
+  /// Cloud-only: the server requested the participant to migrate the connection elsewhere.
   Migration,
+  /// The signal websocket was closed unexpectedly.
   SignalClose,
+  /// The room was closed, due to all Standard and Ingress participants having left.
   RoomClosed,
+  /// SIP callee did not respond in time.
   UserUnavailable,
+  /// SIP callee rejected the call (busy).
   UserRejected,
-  SipTrunkFailure, ///< SIP (telephony) trunk connection failed
+  /// SIP protocol failure or unexpected response.
+  SipTrunkFailure,
+  /// Server timed out a participant session.
   ConnectionTimeout,
-  MediaFailure
+  /// Media stream failure or media timeout.
+  MediaFailure,
+  /// Agent encountered an error.
+  AgentError
 };
 
 /// Application-level user data carried in a data packet.