Desktop app: support multiple windows on Windows for virtual-desktop workflows

Summary

The Claude Code Desktop app on Windows is single-instance: launching the app a second time just focuses the existing window. This blocks a common Windows power-user workflow where each virtual desktop hosts its own app window pinned to a different work stream.

Use case

I routinely run parallel work streams, e.g. code review on Desktop 1, a long-running build/refactor on Desktop 2, research on Desktop 3. With other tools (Chrome, VS Code, Windows Terminal) each window lives on its own virtual desktop and I can Win+Ctrl+Arrow between them. The CC Desktop Sessions sidebar doesn't help here because Windows virtual desktops key off window handles, not in-app tabs.

Requested behavior

1. Allow multiple top-level windows of the Claude Code Desktop app, each able to select a different session/work stream.
2. On app update or restart, restore each window to its previous virtual desktop and screen position (Chrome already does this well via session restore + IVirtualDesktopManager).

Why this is feasible

Electron exposes BrowserWindow.getBounds() for position/size, and the Win32 IVirtualDesktopManager COM API returns the desktop GUID for a window handle. Persisting {bounds, desktopGuid, sessionId} per window on shutdown and replaying on startup is the same pattern Chrome uses.

Workaround today

Run multiple CC CLI instances in separate Windows Terminal tabs pinned to different virtual desktops. Works, but loses the desktop app UX.

Environment

• OS: Windows 11 Enterprise (10.0.26100)
• Claude Code Desktop app (current version)