feat: add Windows desktop lifecycle primitives

[orga-agent]

Summary

• add window close-to-hide/final-close lifecycle
• add WebView messaging, external navigation, and deterministic teardown
• add notification-area menu/restoration and packaged icon support
• terminate the WinUI runtime when the Bare loop drains

Verification

• package tests and lint pass
• Windows x64 native compile passes
• native lifecycle sample and no-window/fatal-exit paths verified through Kepos rehearsal

[orga-agent]

Follow-up from real Windows dogfood:

• Fixed NOTIFYICON_VERSION_4 event decoding: Shell packs the event in LOWORD(lParam) and icon ID in HIWORD(lParam).
• Replaced the message-only callback HWND with a hidden top-level tool window so TrackPopupMenu can own foreground UI and TaskbarCreated broadcasts can restore the icon.
• Enabled right-button menu selection and NIM_SETFOCUS.
• Verified native compilation and Shell_NotifyIconGetRect for the live Kepos process (registered 32x48 notification rect).
• Registered the Windows subscriber with the active WSL publisher and verified all 17 configured local service listeners are present.

The root workflow now invalidates only stale PCH output while preserving downloaded SDK dependencies.