desktop(product): decide launch target-state and replace embedded continuity where required

[Whiteks1]

Summary

Make the explicit product and architecture decision for Launch rather than carrying the current embedded surface forward by inertia.

Includes

• decide native Desktop launch target-state vs transitional continuity
• replace embedded legacy behavior if needed
• keep the decision aligned with the new shell architecture

Done when

• Launch has an explicit target-state
• the desktop no longer relies on accidental embedded continuity for launch UX