A clarify/approval/sudo/secret prompt blocks the turn on the user, but the UI
treated it as an in-flight turn: the "thinking" timer kept ticking and Esc
interrupted the run — discarding a question you might want to come back to. Add
$activeSessionAwaitingInput (the pet's awaitingInput concept, scoped to the
active session) and use it to suppress the stall indicator and disarm Esc while a
prompt waits. Clear the session's prompts (and needsInput) on Stop and on turn
end so a resolved/aborted turn can't leave a dead panel or a stuck "needs input"
dot.