Dragging macOS screenshot preview into Ghostty results in "Path does not exist"

### Describe the bug

When dragging a macOS screenshot preview (from the floating thumbnail) directly into Ghostty, the terminal reports that the file path does not exist. It successfully attaches to the terminal and shows

```
📷 Screenshot 2026-03-14 at 7.56.03 PM.png
```

But shortly thereafter, something tries to perform a read operation and it doesn't exist:

```
✗ Read /var/folders/qf/vys307797xz9g_p6r6cbjdlh0000gn/T/TemporaryItems/NSIRD_screencaptureui_Bth1wV/Screenshot
2026-03-14 at 7.56.03 PM.png
Path does not exist
```

This appears to be related to how macOS handles screenshot previews: when you drag the preview instead of letting it save, the file is never written to disk. However, Ghostty still inserts the temporary path and then reports an error.

The result is a misleading error message (a false positive), since the behavior is expected from macOS but looks like a file-access failure in Ghostty.

### Affected version

1.0.5

### Steps to reproduce the behavior

- Take a screenshot on macOS using Cmd + Shift + 4
- Wait for the screenshot preview thumbnail to appear in the bottom-right corner.
- Drag the preview thumbnail directly into a Ghostty terminal (tested on Ghostty 1.2.3).
- Enter some prompt examining the image.
- The terminal shows that a file path was attached, followed by an error.

### Expected behavior

I avoids displaying an error message when the path corresponds to a macOS screenshot preview that was never saved.

At the moment the message appears to indicate a failure, even though the underlying behavior comes from macOS screenshot handling.

### Additional context

```
[REDACTED] [REDACTED] █████ █████ [📷 Screenshot 2026-03-14 at 7.56.03 PM.png] [REDACTED] [REDACTED] █████ █████

◐ The user wants me to [REDACTED] [REDACTED] █████ █████
Let me first look at the [REDACTED] [REDACTED] █████ █████

✗ Read /var/folders/qf/vys307797xz9g_p6r6cbjdlh0000gn/T/TemporaryItems/NSIRD_screencaptureui_Bth1wV/Screenshot
2026-03-14 at 7.56.03 PM.png
Path does not exist
````