[FEATURE] Add compact/collapsed view for team member roster in team mode

Preflight Checklist

• [x] I have searched existing requests and this feature hasn't been requested yet
• [x] This is a single feature request (not multiple features)

Problem Statement

When using team mode with more than a few agents, the team member roster and status panel consume a significant portion of the terminal viewport. As the team grows, useful output — agent work products, tool calls, decisions — scrolls above the fold and becomes inaccessible. This is compounded by existing terminal rendering issues (flickering, unreliable scrollback — see #10794), which make it difficult to scroll back and recover that output.

The result is that the larger and more capable your team, the harder it is to actually see what they are doing. There is currently no way to collapse, minimize, or hide the team member list to reclaim viewport space for the output that matters.

Proposed Solution

Add a toggle or configuration option to collapse the team member roster into a minimal summary line (e.g., ▸ 5 agents active (2 working, 3 idle)) that can be expanded on demand. Possible implementations:

• Keyboard shortcut — a keybinding (e.g., Shift+H) to toggle between full roster and collapsed summary
• Config flag — team.displayMode: "compact" | "full" in settings to default to collapsed view
• Auto-collapse threshold — automatically switch to compact mode when team size exceeds N agents

In compact mode, the user would still be able to expand the roster on demand or cycle to individual agents with existing keybindings (Shift+Down). The goal is to make the default viewport prioritize agent output over status chrome.

Alternative Solutions

_No response_

Priority

High - Significant impact on productivity

Feature Category

Interactive mode (TUI)

Use Case Example

_No response_

Additional Context

_No response_