Gantt component

[stsrki]

This PR introduces a new Gantt component for Blazorise. It adds a hierarchical tree-and-timeline task view with
declarative columns and views, built-in editing, drag interactions, sorting, keyboard navigation, WBS support, and toolbar
and column-picker controls, localization, and initial test coverage, while also allowing consumers to keep persistence
and edit handling in external callbacks/APIs.

[njannink]

Test 12-03-2026

General findings

• When adding a child doesn't it make sense to add it to the end of the list of current children and default start date-time the end date-time of the last child
• Option to change the order of children and or sort it by start date-time
• Gantt (external editing): Delete has no confirm dialog kind of dangerous

Provider specific UI

• AntDesign
• Bootstrap
• Bootstrap Server
• Bootstrap5
• Bulma
  • Progress slider very short and Duration up/down looks weird
  
• FluentUI2
• Material
• Tailwind
  • Next/previous button sizes
  • Horizontal scrollbar always visible
  • Invisible progress bar is task dialog
    
  • Auras around buttons <> and +

[stsrki]

• When adding a child doesn't it make sense to add it to the end of the list of current children and default start date-time the end date-time of the last child

This can be improved, yes.

As for the other things mentioned, they are out of the scope of work, but I can see which are easy to do.