### Summary
A StatusNotifierItem that briefly enters `NeedsAttention` with an attention icon leaves its tray icon **blank** after the attention state clears. The tray slot keeps its size and stays clickable, but the icon is gone until the item is rebuilt (hide/show) or the shell restarts. Reproduced with EasyEffects 8.2.8 on omarchy 4.0.2 / quickshell 0.3.1.

### Expected
After the attention icon disappears, the tray icon returns to the app's normal icon.

### Actual
The icon goes blank. Hide + show the item (or `omarchy restart shell`) brings it back — so the icon *data* is intact; this is a re-render failure, not data loss.

### Steps to reproduce
1. EasyEffects 8.2.8 running, tray icon visible in the Omarchy bar tray.
2. Click the EasyEffects tray icon → **Output Presets** → pick any preset.
3. EasyEffects shows a 3s tray message (`SystemTrayIcon.showMessage(…, SystemTrayIcon.Information, 3000)`); the icon becomes an info/"i" glyph (SNI `Status=NeedsAttention`, `AttentionIconName=dialog-information`).
4. After ~3s the message clears (`Status` → `Active`) and the EasyEffects icon goes blank and stays blank until the item is hidden/shown or the shell restarts.

### Root cause
`/usr/share/omarchy/shell/plugins/bar/widgets/Tray.qml`, the `TrayIcon` component toggles `Image.layer.enabled`/`visible` based on symbolic-ness:

```qml
Image {
  ...
  visible: !trayIconRoot.symbolic
  layer.enabled: trayIconRoot.symbolic
}
MultiEffect {
  ...
  visible: trayIconRoot.symbolic
}
```

EasyEffects' icon (`com.github.wwmm.easyeffects-symbolic`) is symbolic → rendered through a hidden offscreen layer + `MultiEffect` tint. The attention icon `dialog-information` is not symbolic → plain visible image. Returning to the symbolic icon re-enables the layer with an unchanged image source, leaving the layer texture stale → blank. DBus side is healthy throughout (`Status=Active`, valid `IconName` + pixmaps); the blank only clears on item rebuild.

### Proposed fix
Keep the layer persistent and switch only the tint:

```qml
Image {
  ...
  visible: false
  layer.enabled: true
}
MultiEffect {
  ...
  colorization: trayIconRoot.symbolic ? 1.0 : 0.0
  colorizationColor: root.foreground
}
```

Verified locally by cloning the widget to `~/.config/omarchy/plugins/ant.tray/` and applying the same change — the icon now survives the attention round-trip.

### Environment
- omarchy 4.0.2-1, quickshell 0.3.1-1, easyeffects 8.2.8-1, qt6-base 6.11.2-3, hyprland 0.56.2-1
- Intel i7-1355U, Iris Xe + RTX 3050, Hyprland/Wayland