feat(windows): validate MSB guest creation and agent run on Windows 11 (WHP) #657

🤖: AI agent (OpenCode), filing on behalf of @mogul. Split out of the epic #461 (Increment 2) so it is tracked on its own.

Problem

No live evidence yet that acq can create an MSB guest and run an agent on Windows 11. MSB on Windows requires Windows Hypervisor Platform (WHP), which can need an elevated PowerShell window and a reboot.

Deliverables

• Validate and document WHP setup, including elevation and reboot requirements.
• Run acq run opencode <workspace> on real Windows 11 hardware (or an equivalent machine with WHP available) and capture the observed output.
• Record any blocker as BLOCKED with the exact error rather than working around it.

Acceptance

Captured evidence of a successful MSB guest creation and agent run against a test workspace, plus a docs update covering WHP prerequisites.

Related

#461, #644 (path portability, partly validated on a Windows host), #463 (preview install path).