RpcClient#handleLine was dropping extension_ui_request frames
(no isAgentEvent match → early return). Callers of login() had
no way to learn the auth URL, so the callback-server flow never
got a browser visit and the command hung until timeout.
- Add isRpcExtensionUiRequest type guard
- Add #extensionUiListeners set to RpcClient
- Dispatch extension_ui_request frames through that set in #handleLine
- login() accepts optional { onOpenUrl } callback; registers/
deregisters a listener scoped to the command's lifetime
Addresses: https://github.com/can1357/oh-my-pi/pull/987#discussion_r3213428270
Miroslav Drbal
ae3aa36e3c