feat(core): swiftui lifecycle boot apps to use standard notification observers for windows - #11345

…observers for windows

Replace the process-global flag and discarded observer tokens with NativeScriptWindowCommandCoordinator, which owns the NotificationCenter tokens and registers them once per process. The SwiftUI environment actions (openWindow, dismissWindow, openImmersiveSpace, dismissImmersiveSpace) are rebound on every appearance so commands always dispatch through actions from the current scene rather than ones captured at first launch. Documents the boot-ordering guarantee that observers are installed before the JS runtime can post its first window command, and deletes the unused force-cast parseWindowInfo in favor of a single optional-safe parser.