[FEATURE] Agent Teams: add Windows Terminal split pane support

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

Agent Teams display modes currently support tmux (Linux/macOS) and iTerm2 (macOS) for split pane viewing of teammate activity. On Windows, the only available option is in-process, which shows all teammates in a single pane with Shift+Down to cycle through them.

This makes monitoring 3+ teammates impractical — you can only see one at a time and must manually cycle. Windows is a significant portion of the developer market, and Windows users currently get a degraded Agent Teams experience.

Proposed Solution

Add a display: wt mode that uses Windows Terminal's native CLI for split panes:

wt -w 0 sp -H --title "teammate-1" cmd /c "claude ..."
wt -w 0 sp -V --title "teammate-2" cmd /c "claude ..."

Windows Terminal (default on Windows 11) supports:

• Horizontal (-H) and vertical (-V) splits via wt CLI
• Named panes with --title
• Programmable focus switching
• The wt command is available system-wide

Detection: check if wt.exe is available on PATH (present on all Windows 11 installs and Windows 10 with Windows Terminal installed).

Alternative Solutions

1. display: web — a localhost web dashboard showing all teammate activity in a browser (cross-platform, would work everywhere)
2. display: log — each teammate writes to a separate log file, user monitors with tail -f or similar
3. Current workaround: using in-process mode and cycling through teammates with Shift+Down — functional but impractical for 3+ teammates

Priority

Medium - Would be very helpful

Feature Category

Interactive mode (TUI)

Use Case Example

1. I have a conductor agent that spawns 3-4 teammates (laravel-dev, frontend-dev, security-auditor, code-reviewer)
2. I want to monitor all teammates working simultaneously
3. With display: wt, Windows Terminal would split into panes, each showing a teammate's progress in real time
4. This matches the experience that tmux/iTerm2 users already have on Linux/macOS

Additional Context

• This is documented as a known limitation in the official docs
• Windows Terminal wt CLI reference: https://learn.microsoft.com/en-us/windows/terminal/command-line-arguments
• The wt approach is analogous to how tmux and iTerm2 modes work — launching subprocesses in terminal-managed panes
• Agent Teams is an experimental feature enabled via CLAUDE_CODE_EXPERIMENTAL_AGENT_TEAMS=1