fix: creating a room failed with a blank "Failed to copy room"

The 2023 client sends rooms/{id}/clone through the same RecNet rooms
helper as "save room" and "restore subroom save", which reads the
{success, value, error} envelope. The clone handler answered with the
bare room details, so the client found no success flag and rejected the
reply with an empty error, even though the room had been created.

Clone now returns the envelope with the full room details in value, and
refusals (unknown source, cloning not allowed) are a 200 with
success=false and a message instead of a bodyless 404/403.

docs/recroom-2023-room-save.md

@@ -89,8 +89,15 @@ body — the same `roomserver/` prefix as every other room mutation from
 that client. A bare-only `rooms/{id}/clone` route 404s with an empty
 body, which the client's promise layer surfaces as a message-less
 `Failed to copy room: Exception of type 'CEMNLBKJABA' was thrown`.
-The response must be the FULL room-details object (`FGCPNAACHIK`,
-same shape as `GET roomserver/rooms/{id}`), not a status wrapper.
+The response is the legacy `{success, value, error}` envelope, the same
+one "save room" and "restore subroom save" use: the clone goes through the
+same RecNet rooms helper (`NLDBPDCNNCF.BDBHCEGKGDC`, which takes an op
+name). `value` is the FULL room-details object (`FGCPNAACHIK`, same shape
+as `GET roomserver/rooms/{id}`). A bare room-details body has no `success`,
+so the client rejects it with an empty error and shows the same
+message-less `Failed to copy room`, even though the room was created.
+Refusals (unknown source, cloning not allowed) are HTTP 200 with
+`success: false` and the message in `error`.
 
 Blob semantics on clone (`RoomsModerationController.BareClone`):