Support configurable stacked/offset window layouts in FancyZones

### Description of the new feature / enhancement

I'd like FancyZones to support configurable stacked (cascading) window layouts, where multiple windows assigned to a group or zone are automatically positioned with a configurable X/Y offset instead of occupying the exact same rectangle.

For example:

- Base position: (100, 100)
- Window 1: (100, 100)
- Window 2: (120, 120)
- Window 3: (140, 140)

This would make it easy to keep several related windows visible while still organizing them as a single workspace.

Suggested options:

- Horizontal offset (pixels)
- Vertical offset (pixels)
- Maximum visible stack size
- Bring selected window to the top while preserving the stack

### Scenario when this would be used?

Use cases:

- Comparing multiple documents
- Multiple terminal windows
- Browser windows for related tasks
- Chat/email applications
- Keeping reference material visible without fully tiling every window

This would complement the existing tiling layouts by providing an organizational pattern between full overlap and full tiling.

### Supporting information

_No response_

Start by locating the FancyZones component and its existing layout behavior. Clarify how stacked groups, horizontal and vertical offsets, maximum visible windows, and bringing a selected window to the top should interact with current layouts. Done means the behavior and configuration are implemented and verified for the listed window-management scenarios.

Written by the indexing model from the issue text.