[BUG] Console window steals focus during background operations on Windows 11

What's wrong?
Every time the Claude Desktop Windows app performs a background operation, a console/bash window appears and steals focus from the active window. This actively interrupts typing and breaks workflow — it's not just a taskbar flash.

Environment

• Platform: Claude Desktop (Windows app)
• OS: Windows 11
• Installed via: claude.ai/download

Steps to reproduce

1. Install Claude Desktop on Windows 11
2. Open the app and start a conversation
3. Observe that a black console window appears and steals focus from whatever the user is currently doing, repeatedly throughout the session

Expected behavior
Background subprocesses should run silently with no visible window and without stealing focus.

Root cause (suspected)
Child processes (bash/cowork-svc) are spawned without the CREATE_NO_WINDOW flag — same underlying cause as #28138.

Related issues
#28138, #16880

Impact
High — focus theft actively interrupts typing and makes the desktop app unusable for sustained work.