Scrollback compression was available only through explicit PageList
calls, so normal renderer-backed surfaces never reclaimed cold history.
Debounce renderer wakeups with a one-shot timer and run bounded
compression steps only when the terminal lock is immediately available.
Timer state is isolated in the renderer and becomes idle once PageList
reports that the pass is complete.
Keep inspector reads representation-preserving by decoding compressed
pages into temporary copies. Update the scrollback configuration and
benchmark documentation to describe the production behavior and its
memory accounting.
461562ca4f