Element "Stack" - multiply effect

• I agree to follow the Code of Conduct that this project adheres to.
• I have searched the issue tracker for a feature request that matches the one I want to file, without success.

Is your feature request related to a problem? Please describe.
A very typical need in drawing architectural diagrams is that you want to indicate that one block is dynamically scaling, or multiple items exist. e.g. having many users, or a service which exists many times. Doing this in a clean consistent way is currently not easily possible in Draw.io and requires some workarounds.

Describe the solution you'd like
A new "effect" triggers a mechanism that the element is drawn in a typical stack fashion:

• Connectors would still go to the main element
• Visual aspects (how many duplicate draws, direction and angle could be configurable properties)

Describe alternatives you've considered

• In some cases I resort to separate annotations
• In some cases I just use the manual stacking with grouping (but its hard to properly maintain)
• In some cases I just add some multiplier labels like x100 in the box itself.

Additional context
This allows also AI agents to read the visual intent more semantically than relying on some guidance that "close overlapping stacked elements mean some kind of multiplicity/scaling".

No files, tests, or entry points are named in the issue. Start by locating the existing element-effect and shape-rendering paths, then determine how effect properties are configured. Done means a Stack effect renders configurable duplicate elements with direction and angle options while connectors remain attached to the main element.