Images Preview does not provide a way to copy or save images

- Copilot Chat Extension Version: Built-in Copilot experience
- VS Code Version: Insiders
- OS Version: macOS
- Feature (e.g. agent/edit/ask mode): Agents window image gallery / Images Preview
- Selected model (e.g. GPT 4.1, Claude 3.7 Sonnet): N/A
- Logs: N/A

Steps to Reproduce:

1. Open an agent session that contains multiple generated or attached images.
2. Click an image to open Images Preview.
3. Right-click the displayed image or try the standard copy shortcut.

Expected:

The displayed image can be copied or saved. When the image comes from a file, its source can also be opened or revealed.

Actual:

Images Preview supports navigation and zooming, but provides no way to copy, save, open, or reveal the displayed image. The browser or operating-system image context menu is not available, which leaves users unable to get images out of the gallery.