### What happened

Desktop notifications forwarded through Ghostty (e.g. from Claude Code running in a terminal, or any other app that sends terminal-bell/OSC-style notifications) always show a generic placeholder icon in the Omarchy Quickshell notification popup, instead of Ghostty's own icon.

### What I expected

The notification popup to show Ghostty's app icon, the same way it appears for the app in `com.mitchellh.ghostty.desktop` (`Icon=com.mitchellh.ghostty`), which is correctly installed under `/usr/share/icons/hicolor/*/apps/com.mitchellh.ghostty.png`.

### Root cause

Captured the actual `org.freedesktop.Notifications.Notify` D-Bus call with `dbus-monitor` while Claude Code sent a notification from inside Ghostty:

```
method call ... member=Notify
   string ""                                  # app_icon (empty)
   uint32 0
   string ""
   string "Claude Code"                       # app_name
   string "Screenshot test for the Omarchy bug report — placeholder icon"
   array [ string "default" string "" ]
   array [
      dict entry( string "desktop-entry" variant string "com.mitchellh.ghostty" )
      dict entry( string "urgency" variant byte 1 )
      dict entry( string "image-path" variant string "com.mitchellh.ghostty" )
   ]
   int32 -1
```

Ghostty leaves `app_icon` empty and instead identifies itself via the `desktop-entry` hint (`com.mitchellh.ghostty`), with `image-path` also set to that same string (an icon-theme *name*, not a URI).

In `shell/plugins/notifications/components/NotificationCard.qml`:

```qml
readonly property string smallIconSource: image.length > 0 ? image : iconSource(appIcon)
```

This only ever looks at the Quickshell `Notification.image` and `Notification.appIcon` properties. It never reads `Notification.desktopEntry`. Since:

- `appIcon` is literally `""` here, `iconSource(appIcon)` → `Quickshell.iconPath("", true)` resolves to nothing.
- `image` comes from the `image-path` hint, which per the freedesktop spec may be either a URI *or* a themed icon name — here it's a bare icon-theme name (`com.mitchellh.ghostty`), not a URI, so it isn't usable directly as an `Image.source` and doesn't get resolved through `Quickshell.iconPath`.

Both paths come back empty/unusable, so the card falls back to the generic placeholder glyph — even though the icon Ghostty is pointing at (`com.mitchellh.ghostty`, via either hint) is installed and resolves fine through `Quickshell.iconPath("com.mitchellh.ghostty", true)`.

This isn't Claude-specific — any notification forwarded through Ghostty hits the same path, since Ghostty always sends this same empty-`app_icon` + `desktop-entry`/`image-path`-hint shape.

### Suggested fix

In `NotificationCard.qml` (or wherever `image`/`appIcon` are resolved before reaching the card), add a fallback chain that also tries `desktopEntry`, and treats `image`/`image-path` as a themed icon name (via `Quickshell.iconPath`) when it isn't a URI, e.g. roughly:

```qml
readonly property string smallIconSource:
  image.length > 0 ? image
  : appIcon.length > 0 ? iconSource(appIcon)
  : desktopEntry.length > 0 ? iconSource(desktopEntry)
  : ""
```

(with `image` itself also going through `iconSource()`/`Quickshell.iconPath()` when it isn't already a resolvable URL).

### Steps to reproduce

1. On Omarchy with Ghostty as the terminal, run any program that sends a terminal notification (e.g. Claude Code finishing a task, or `notify-send` isn't needed — Ghostty's own OSC-triggered D-Bus notification is enough).
2. Watch the Quickshell notification popup.
3. Instead of Ghostty's icon, a generic placeholder glyph is shown.

### System details

- Omarchy: 4.0.4-1
- Quickshell: 0.3.1-1
- Ghostty: 1.3.1-arch2
- Hyprland: 0.56.2
- Kernel: 7.2.5-3-omarchy-bore

### Screenshot

Notification popup showing the placeholder icon (top right) 

<img width="599" height="171" alt="Image" src="https://github.com/user-attachments/assets/05d58971-90db-4dfe-875a-959d2ff5e856" />