feat(menu): add @Composable tray menu DSL

[kdroidFilter]

Summary

Lets users call painterResource() and other @Composable functions directly inside Tray { … } and SubMenu { … } — no more hoisting val icon = painterResource(...) above application { … }.

application {
    Tray(icon = painterResource(Res.drawable.icon), tooltip = "App") {
        SubMenu(label = "Advanced", icon = painterResource(Res.drawable.advanced)) {
            Item(label = "Reload", icon = painterResource(Res.drawable.reload)) { /* … */ }
        }
    }
}

How it works

• ComposableTrayMenuScope — new public interface. Every method is @Composable and submenu lambdas are @Composable too, so composable calls work at every level.
• RecordingComposableScope — captures the DSL calls during composition into a flat MenuOp tree, then replays them into the existing TrayMenuBuilder consumed by the native (Windows / Linux / macOS / AWT) impls. The native side is unchanged.
• New Tray() composable overloads for Painter, ImageVector, DrawableResource, iconContent, and the polymorphic Windows-vs-mac-linux variants — all accepting @Composable ComposableTrayMenuScope.() -> Unit.
• @LowPriorityInOverloadResolution on the existing Tray() composables. The new scope is a strict superset of TrayMenuBuilder (adds a no-op dispose(), DrawableResource overloads, legacy CheckableItem(onToggle)), so existing demos auto-resolve to the new API without source changes.
• PainterResourceWorkaroundDemo → DemoComposableMenu — the workaround the old demo taught is no longer needed.

Notes

• Uses kotlin.internal.LowPriorityInOverloadResolution with @file:Suppress("INVISIBLE_REFERENCE", "INVISIBLE_MEMBER") — internal stdlib annotation, widely used in practice but officially unsupported.
• Recording introduces a small per-composition cost (running the user lambda twice — once for hashing, once for replay). Negligible for tray menus.

Test plan

• ./gradlew build passes (main + demo modules + ktlint)
• Run DemoComposableMenu on Linux — menu opens, icons render in items and submenus, click handlers fire
• Run DemoComposableMenu on Windows — same
• Run DemoComposableMenu on macOS — same
• Spot-check an existing demo (e.g. DemoWithDrawableResources) — confirms backward-compat resolution to new API still renders icons correctly
• State-driven menu rebuild: toggle CheckableItem and verify the native menu reflects the new state on next open