feat: Improve preview interaction and size

[ZhBF]

Motivation

The current preview feature is useful, but the preview area can feel quite constrained, especially for large images and long text files. Because the preview is strictly limited within the current window bounds, it often does not provide much more information than the original item view.

For large images in particular, the preview may still be too small to inspect details clearly. I understand that this may be difficult to improve because the project uses GPUI, but I think this is an important UX issue that is worth dedicated attention.

Proposed Solution

A possible preview interaction could work like this:

1. When the user holds the Space key, the preview of the currently selected item appears smoothly.
2. When the user releases the Space key, the preview disappears smoothly.
3. For images, while holding Space, the mouse wheel can zoom in and out of the previewed content.
4. If the previewed content becomes larger than the maximum preview area, the user can drag it with the left mouse button to inspect details freely.

This would make the preview feel closer to a quick, temporary inspection mode.

In addition, it would be helpful if the preview area could be made larger or less strictly constrained, so that previews provide enough visual space to reveal meaningful details.

Alternatives Considered

No response

Acceptance Criteria

• [] Holding the Space key opens a preview for the currently selected item.
• [] Releasing the Space key closes the preview.
• [] Image previews support mouse-wheel zooming while the preview is open.
• [] Zoomed-in image previews support left-button drag-to-pan when the content exceeds the visible preview area.
• [] The preview area is large enough to provide meaningful additional information for large images and long text files.

Scope

gui

[StudentWeis]

nice idea

[StudentWeis]

I think we can open a new window when previewing.