Screen Ruler

### Description of the new feature / enhancement

Add an option to Screen Ruler to use global coordinates across multiple monitors instead of restarting coordinates on each screen.

Currently, when moving the ruler to another monitor, the position resets to zero relative to that monitor. In multi-monitor setups, especially for development, design, or automation workflows, it would be much more practical to have a “virtual desktop coordinates” mode that uses the full Windows desktop space.

Example:

Left monitor: negative X coordinates
Main monitor: X=0
Right monitor: continuous coordinates

Ideally, there could be two modes:

“Per-monitor coordinates” (current behavior)
“Global desktop coordinates” (new option)

This would make Screen Ruler significantly more useful in multi-monitor environments.

### Scenario when this would be used?

This would be used in any multi-monitor setup where I need to measure or reference positions across screens as a single, continuous workspace.

Examples include:

UI/UX design and layout alignment across screens
Development and debugging of applications that span multiple monitors
Creating automated scripts or macros that rely on absolute screen coordinates
Taking screenshots or capturing regions that span across monitors

Having global coordinates would save time and reduce confusion, as I could rely on one consistent coordinate system instead of recalculating positions each time I move to a different monitor.

### Supporting information

This behavior is different from other tools and Windows APIs that already work with global desktop coordinates.

For example, AutoIt's MouseGetPos() returns coordinates relative to the entire virtual desktop (including negative values for monitors on the left), which is extremely useful in multi-monitor environments.

Many users in developer and designer communities have requested similar functionality for more accurate cross-monitor measurements.

Implementing this option would greatly improve productivity for advanced users working with multiple displays.

Start by locating the Screen Ruler implementation and its current per-monitor coordinate handling. Compare the existing behavior with Windows virtual desktop coordinates, including negative values for monitors on the left. Done means the ruler offers per-monitor and global desktop coordinate modes and works consistently across multiple monitors.

Written by the indexing model from the issue text.