fix(proxy): detect Windows Codex desktop MSIX installations

[Filip-Stastny-Philips]

Summary

Fix codemie proxy connect --codex-desktop reporting the app as missing on Windows when it is installed as the registered OpenAI.Codex MSIX package. The existing detector only checks two legacy ChatGPT folders.

Changes

• Preserve existing folder detection and add a Windows-only current-user package lookup through bundled Windows PowerShell, with a 10-second timeout and JSON/UTF-8 output.
• Use the registered install location without scanning protected WindowsApps directories or hardcoding package versions, architecture, or install volume. Discovery errors return the existing not-detected result.
• Await discovery in the connect runner, skip it for forced runs, and include the MSIX lookup in the Windows failure message. Adapt the two existing detection assertions to the async result.

Impact

On the affected Windows 11 device, CodeMie 0.15.8 misses OpenAI.Codex_26.1007.2314.0_x64__2p2nqsd0c76g0. The exact PowerShell query used by this change was manually verified on that device from PowerShell 7: it returned the registered install location with exit code 0.

Validation

• Passed: license check, full lint, typecheck, and build on macOS.
• Passed: related proxy/connector tests and typecheck run by the pre-commit hook.
• Local secrets scan opted out with explicit approval because no container engine is available; GitHub CI must run the secrets scan.
• Windows patched-CLI validation is pending: build this branch, run proxy connect --codex-desktop without --force, restart the desktop app, and confirm a small model request succeeds.

Checklist

• Self-reviewed
• Manual testing performed (package lookup verified; patched CLI/desktop request pending)
• Documentation updated (local investigation report; no public setup change)
• No breaking changes (internal discovery helper is now async; caller and assertions updated)