CMP-7106 Use separate ComposableTargetMarker for desktop menu API
Invalid API mixing such as putting UI composables into menu DSL (or vice versa) can fail at runtime due to applier mismatch. This change improves compile-time detection and reduces runtime-only failures.

• Added desktop-specific marker annotations: MenuComposable
• Marked menu APIs with MenuComposable where menu applier is expected
• Kept applier-creating entrypoints open where appropriate with @ComposableOpenTarget(-1).
• Refactored menu bar composition internals: replaced list adapter usage with direct JMenuBar applier (SwingApplier-based path)

Testing

Window(onCloseRequest = ::exitApplication) {
    MenuBar {
        Text("Label 1")
    }
}
Tray(icon) {
    Text("Label 2")
}

Now produces

Calling a UI Composable composable function where a Menu Composable composable was expected

Release Notes

Features - Desktop

• New compile-time warnings for invalid ui/menu composable mixing that previously failed only at runtime.