Proposal: add atomic tool output mode

I would like to add three Ctrl+O tool-output modes: collapsed, expanded, and atomic. Atomic mode renders tool output as one-line rows with no left padding while preserving each spinners original position. The mode change also needs to reach offscreen, nested, and pending tool components.

Expanded output becomes too long during tool-heavy sessions, while collapsed output hides useful progress. This change provides a compact middle ground and fixes cases where only some tool components receive the selected output mode.

Start by tracing the Ctrl+O handler and the collapsed and expanded tool-output components, including offscreen, nested, and pending cases. Done means atomic mode is selectable, renders one-line rows without left padding, preserves each spinner's original position, and the selected mode reaches every listed component.

Written by the indexing model from the issue text.