feat(trayapp): trim the heap after the popup is hidden

[kdroidFilter]

Summary

• The TrayApp popup keeps its composition alive while hidden (state survives hide/show), so garbage from the visible session lingers for as long as the app idles in the tray — exactly the footprint users check in the task manager.
• Trigger a GC ~1.5 s after the exit animation completes, in both implementations (standalone panel on Windows/macOS, window on Linux).
• No visible jank: nothing is on screen when the collection runs, it executes off the UI thread, and reshowing the popup restarts the visibility effect which cancels the pending delay — rapid toggles never GC.
• Audio-safe with native playback backends (e.g. composemediaplayer/rodio): their pipelines run on non-JVM threads, which JVM safepoints do not pause.

Test plan

• macOS: open popup, close it — memory drops ~2 s later, no visual glitch
• Rapid open/close toggles do not trigger repeated collections
• Linux window impl: same behavior on hide